AS BIOLOGY 9700 PAPER 1 | May/June 2022 | Paper 12 | 9700/12/M/J/22 | SOLVED

00:55:44
https://www.youtube.com/watch?v=3Ye00gJi-3g

Summary

TLDRThe video is a live review session for Cambridge International AS Level Biology Paper 1 (9700), May/June 2022, where the presenter goes through the exam questions while explaining biological concepts. The session highlights the paper's difficulty level through the threshold marks and provides answers with detailed explanations for questions on magnification, resolution, cell structure functions, and enzymes. The host shares insights from his medical school experience, engages with viewers about their exam preparation, and emphasizes the importance of understanding various biology topics. Overall, it serves as a comprehensive guide for students preparing for the exam while also aiming to improve the reach of biology content online.

Takeaways

  • 📚 Understanding threshold marks can help gauge paper difficulty.
  • 🔬 Magnification formulas are crucial for microscopy questions.
  • 🧬 Red light has lower resolution compared to green light.
  • 🔍 Cell structure functions need to be matched accurately.
  • 💡 Enzyme affinity affects substrate concentration and efficiency.

Timeline

  • 00:00:00 - 00:05:00

    The presenter explains that they will solve the Biology Paper 9700/12 from the May/June 2022 series while encouraging viewers to subscribe for more content. They discuss the threshold marks for this particular paper, stating it's slightly harder compared to other variants.

  • 00:05:00 - 00:10:00

    They begin solving question number one, relating magnification and the use of a microscope. The presenter reflects on how to calculate the actual size based on image size and magnification. They explain using both green and red light in microscopy, noting impacts on magnification and resolution, particularly how red light decreases resolution due to a longer wavelength.

  • 00:10:00 - 00:15:00

    In question two, the presenter matches cell structures to their functions, confirming knowledge of the smooth endoplasmic reticulum, ribosomes, and centrioles. They discuss their experience in med school and how they want to focus on recent exam papers first before addressing older material.

  • 00:15:00 - 00:20:00

    The presenter continues processing various questions related to biology concepts like chloroplasts, mitochondria, and non-viruses, with emphasis on details such as ribosomes' presence and extraction methods.

  • 00:20:00 - 00:25:00

    Discussing plant extracts and testing with Benedict's solution, the presenter describes how to determine the quantity of reducing sugar in a sequence of plant extracts, explaining the color changes during the process, with blue being the lowest sugar content and red the highest.

  • 00:25:00 - 00:30:00

    They analyze the importance of understanding various biological polymers and the significance of polymers like cellulose and glycogen, affirming the importance of understanding different carbohydrate structures in preparation for exams.

  • 00:30:00 - 00:35:00

    Questions about peptide bonds, water's properties, and enzymes follow, as the presenter effortlessly transitions from one topic to another, highlighting critical facts about molecular structure and metabolic interactions.

  • 00:35:00 - 00:40:00

    Emphasizing the distinctions in saturated and unsaturated fatty acids based on environmental conditions, they argue that short-chain unsaturated fatty acids are necessary for mammals in cold climates, explaining the relevance to triglyceride formation.

  • 00:40:00 - 00:45:00

    The discussion moves toward the function of a salt solution in experiments, where they explain the purpose of isotonic solutions in biological settings to maintain cell integrity during procedures.

  • 00:45:00 - 00:55:44

    Finally, the presenter wraps up with questions regarding the structure of adipose tissue and generalizations about the circulatory system, concluding by inviting viewers to subscribe and mentioning additional resources available on the channel.

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Mind Map

Video Q&A

  • What concepts are covered in the review?

    The review covers topics like magnification, resolution, cell structures, enzyme functions, DNA replication, and the human gas exchange system.

  • How does the presenter engage with the audience?

    The presenter encourages viewers to subscribe, comments on their paper requests, and addresses any mistakes or clarifications needed.

  • What are the threshold marks mentioned?

    The threshold marks for the paper were A: 27, B: 23, C: 19, D: 16, E: 13.

  • What expertise does the presenter have in biology?

    The presenter is in medical school and has a strong background in biology, having achieved high scores in previous biology examinations.

  • What is the focus of the video?

    The focus is on solving the biology exam paper, explaining each question and answer in detail.

View more video summaries

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  • 00:00:00
    hi guys we're solving this bio paper
  • 00:00:03
    today
  • 00:00:04
    this is nine seven zero zero
  • 00:00:08
    paper one two May June 2022
  • 00:00:15
    if you like the videos remember to
  • 00:00:17
    subscribe to the channel it would help
  • 00:00:18
    me a lot
  • 00:00:19
    I plan to do paper one three after this
  • 00:00:22
    as soon as I can before your exam on the
  • 00:00:25
    16th all right
  • 00:00:28
    anyway let's take a look at the
  • 00:00:30
    threshold before we begin
  • 00:00:31
    so paper one to a slightly harder than
  • 00:00:34
    paper one one according to the threshold
  • 00:00:38
    for paper one two the a was at 27b was
  • 00:00:41
    at 23 C was at 19. 27 23 and 19.
  • 00:01:00
    what about D and E
  • 00:01:02
    so D was at 16 e was at 13.
  • 00:01:07
    so yeah clearly compared to the other
  • 00:01:09
    variants
  • 00:01:11
    uh you can see that the mark 4A was very
  • 00:01:14
    low three to four marks lower than the
  • 00:01:16
    other variants so it was a difficult
  • 00:01:19
    paper so let's see
  • 00:01:21
    how it goes all right
  • 00:01:23
    let's begin
  • 00:01:26
    [Music]
  • 00:01:28
    starting with question number one
  • 00:01:29
    [Music]
  • 00:01:32
    honestly I can't do this using
  • 00:01:36
    my PC
  • 00:01:38
    because we need to print this all right
  • 00:01:42
    so it's like this
  • 00:01:45
    do you know that the formula is Mia
  • 00:01:47
    right m is equal to I by a magnification
  • 00:01:50
    equals the image by actually
  • 00:01:52
    so I'm gonna go reverse I know the
  • 00:01:55
    Marxism answer is C okay
  • 00:01:58
    so let's see this is how you're gonna do
  • 00:02:01
    it magnification is 360.
  • 00:02:07
    wait up
  • 00:02:10
    to turn promise six
  • 00:02:21
    all right so approximately the maximum
  • 00:02:24
    diameter right so you guys need to take
  • 00:02:26
    this length
  • 00:02:27
    this maximum one
  • 00:02:29
    so when you measure this with a scale if
  • 00:02:31
    you have this printed paper it should
  • 00:02:33
    measure about five centimeters so five
  • 00:02:35
    centimeters with your scale is around
  • 00:02:37
    it's basically 5.0 into 10 to the power
  • 00:02:40
    minus 2 meters right divided by actual
  • 00:02:42
    so actual is 5.0 into 10 to the power
  • 00:02:44
    minus 2 divided by 360.
  • 00:02:49
    foreign
  • 00:02:58
    minus 4 meters into 10 power 6
  • 00:03:02
    is basically
  • 00:03:05
    138.9 or basically 140 micrometer that's
  • 00:03:09
    how you're gonna get C okay
  • 00:03:11
    that's how you do it next
  • 00:03:13
    one is observed twice with a microscope
  • 00:03:16
    firstly is in green light with the waved
  • 00:03:18
    in the 510 and then using red light with
  • 00:03:20
    a wavelength of 650 nanometers what
  • 00:03:22
    happens to the magnification and
  • 00:03:24
    resolution when using red light to
  • 00:03:26
    compare to green lights
  • 00:03:28
    so basically guys red light has greater
  • 00:03:31
    wavelength so the smaller the wavelength
  • 00:03:33
    the greater the resolution because
  • 00:03:34
    according to the definition resolution
  • 00:03:35
    is half the
  • 00:03:37
    wavelength of light used so here it's
  • 00:03:40
    not that much it's actually 325 using
  • 00:03:42
    red light while for green light it's
  • 00:03:44
    basically
  • 00:03:45
    [Music]
  • 00:03:50
    255 okay so that's uh smaller wavelength
  • 00:03:54
    means greater resolution
  • 00:03:56
    red light and green light
  • 00:04:00
    made me think about squid game
  • 00:04:03
    so basically when we
  • 00:04:06
    use red light our resolution decreases
  • 00:04:10
    that is why our answer is automatically
  • 00:04:13
    see there is no other option and
  • 00:04:15
    magnification doesn't really change
  • 00:04:17
    because we don't really change the
  • 00:04:19
    objective lens
  • 00:04:20
    right or the eyepiece
  • 00:04:23
    first transfer us to match the function
  • 00:04:25
    with the appearance of some cell
  • 00:04:27
    structures in an animal cell the
  • 00:04:29
    functions are listed by number
  • 00:04:30
    oh this is quite similar to variant one
  • 00:04:33
    one since it is of lipids this is
  • 00:04:35
    basically smooth ER synthesis of
  • 00:04:39
    polypeptides this is basically rough
  • 00:04:41
    year or the ribosome essentially
  • 00:04:45
    because this is the mitotix window
  • 00:04:46
    centriole we also had this in a variant
  • 00:04:49
    uh one one the one I just did recently
  • 00:04:53
    so guys if you have other paper requests
  • 00:04:55
    please feel free to comment below I
  • 00:04:58
    tried to reply to the comments as much
  • 00:04:59
    as possible I don't tend to do older
  • 00:05:02
    years you see like I want to finish the
  • 00:05:05
    recent years before going to the
  • 00:05:07
    previous ones
  • 00:05:09
    uh I'll try to listen to your requests
  • 00:05:11
    though but I have the I have the
  • 00:05:14
    complete 2021 series solved so you could
  • 00:05:17
    see those videos
  • 00:05:19
    and I'm trying to finish 2022 before
  • 00:05:21
    your exam so hoping for the best
  • 00:05:24
    anyway
  • 00:05:25
    so
  • 00:05:27
    we should match to the numbered
  • 00:05:30
    functions with the appearance of the
  • 00:05:32
    cell structure
  • 00:05:34
    so centrioles it's a non-membranous
  • 00:05:39
    cylindrical structure okay that's why
  • 00:05:42
    basically
  • 00:05:43
    so one has to be y guys
  • 00:05:46
    now since it's a positive touch that's
  • 00:05:48
    mainly the ribosome honestly so the
  • 00:05:50
    ribosome is also a
  • 00:05:53
    you know the ribosome is also a
  • 00:05:54
    non-membraneous structure
  • 00:05:58
    and it is spherical in nature that is
  • 00:06:01
    why I'm gonna go with c
  • 00:06:02
    because this is the centriole this is
  • 00:06:07
    the ribosome so we we got that
  • 00:06:10
    and the last one sentence of lipids it's
  • 00:06:13
    basically remembrance with the sound and
  • 00:06:15
    enclosed in our cavity this is the
  • 00:06:17
    smooth ER so C makes sense
  • 00:06:20
    this is the nuclear
  • 00:06:23
    membrane
  • 00:06:25
    and remember this is the Golgi body
  • 00:06:31
    by the way guys I'm actually in med
  • 00:06:33
    school so bio is my main subject
  • 00:06:36
    I also got a country highest in A2
  • 00:06:40
    biology back in the day I had a score of
  • 00:06:42
    95 22 and 93 is
  • 00:06:46
    uh but yeah I tend to make more physics
  • 00:06:49
    and chemistry videos mainly because they
  • 00:06:52
    get more reach
  • 00:06:53
    it's like bio videos get less rich and I
  • 00:06:57
    guess the percentage of people with bio
  • 00:06:59
    is quite less compared to physics and
  • 00:07:01
    chemistry it seems
  • 00:07:03
    uh but if these videos do get an abuse
  • 00:07:06
    I'm gonna try to make more bio videos
  • 00:07:07
    including paper two and paper 4 for the
  • 00:07:09
    future right I also plan to do more math
  • 00:07:12
    videos in the future as well hopefully
  • 00:07:17
    also I'm gonna be done with med school
  • 00:07:19
    in 1.5 years
  • 00:07:21
    then I plan to move to the UK hopefully
  • 00:07:25
    moving on number four what is found in
  • 00:07:28
    chloroplasts and mitochondria
  • 00:07:31
    basically they are prokaryotes so they
  • 00:07:34
    contain 70 ribosomes as well as circular
  • 00:07:38
    DNA
  • 00:07:40
    which feature is correct for all
  • 00:07:41
    non-viruses
  • 00:07:43
    basically guys they might have DNA or
  • 00:07:46
    RNA this is very similar to variant one
  • 00:07:48
    one actually they have capsids made up
  • 00:07:51
    of lipids and proteins this lipid part
  • 00:07:54
    is wrong it should be protein only a is
  • 00:07:56
    wrong outer envelope of phosphate but
  • 00:07:59
    this is wrong yeah they are non-seller
  • 00:08:01
    five is D okay
  • 00:08:03
    please uh you know when doing yours I
  • 00:08:06
    would suggest just do the three variants
  • 00:08:08
    simultaneously
  • 00:08:10
    do you guys understand because then
  • 00:08:12
    you're gonna see the resemblance between
  • 00:08:14
    the papers and your concept will be more
  • 00:08:17
    clear since you'll find out all the
  • 00:08:19
    variations that Cambridge can give you a
  • 00:08:21
    bio paper one tends to be a bit
  • 00:08:23
    difficult but you'll get the hang of it
  • 00:08:25
    over time so hopefully you guys have
  • 00:08:27
    enough time to improve
  • 00:08:29
    four extracts from different plant
  • 00:08:31
    materials were made and tested with
  • 00:08:32
    biantic solution the extracts were
  • 00:08:34
    boiled with Bendix version for 240
  • 00:08:36
    seconds
  • 00:08:37
    and the final color was recorded which
  • 00:08:40
    sequence of plant extracts represents an
  • 00:08:43
    increasing quantity of reducing sugar
  • 00:08:45
    okay so red is the highest
  • 00:08:49
    so basically one should be at the end so
  • 00:08:51
    we're gonna go with d you don't need to
  • 00:08:52
    look at the other options this is how
  • 00:08:55
    you uh do McQ is faster by the way this
  • 00:08:57
    is what I did back in the day but you
  • 00:08:59
    can still check blue is the least color
  • 00:09:01
    so it will start from three
  • 00:09:03
    so three is the first one so it goes
  • 00:09:05
    from Blue
  • 00:09:07
    okay to Green
  • 00:09:10
    to Yellow to Red this is the order
  • 00:09:13
    which properties which are properties
  • 00:09:15
    that are dependent on hydrogen plus
  • 00:09:17
    cellulose this is correct water this is
  • 00:09:19
    also true hemoglobin is a protein so yes
  • 00:09:22
    this is also true seven is a eight which
  • 00:09:25
    statement is correct this is also
  • 00:09:27
    similar to variant one one cellulose
  • 00:09:29
    glycogen and amylopectin are all
  • 00:09:32
    polymers
  • 00:09:33
    um yes I agree these are all
  • 00:09:34
    polysaccharides right
  • 00:09:37
    basically amylopectin and amylose make
  • 00:09:40
    up starch but it's supposed to credit so
  • 00:09:42
    they are polymers
  • 00:09:44
    Sailors is made up of beta
  • 00:09:47
    beta glucose and the others are made up
  • 00:09:49
    of alpha glucose okay so why are the
  • 00:09:51
    other ones wrong if you're wondering
  • 00:09:53
    starch is not a monomer
  • 00:09:55
    sucrose is not this is not a
  • 00:09:57
    polysaccharide ribose is just a
  • 00:09:59
    monosaccharide come on
  • 00:10:01
    so it's wrong okay
  • 00:10:03
    nine the diagram shows two amino acids
  • 00:10:05
    not the hydrogen atoms are numbered one
  • 00:10:07
    to six which two numbered hydrogen atoms
  • 00:10:09
    could contribute to the production of a
  • 00:10:11
    molecule of water when a peptide bond
  • 00:10:13
    forms between the two amino acids
  • 00:10:16
    the essentially are peptide bone forms
  • 00:10:18
    between
  • 00:10:19
    the carboxyl end of one I'm an acid and
  • 00:10:23
    the amine group of another one
  • 00:10:25
    or basically here it can either be it
  • 00:10:28
    can also be this let me do the color
  • 00:10:30
    coding six can bind with one so it's
  • 00:10:33
    either three four or one six three four
  • 00:10:36
    or one six
  • 00:10:40
    uh
  • 00:10:43
    wait what
  • 00:10:49
    three four oh yeah one six yeah so it's
  • 00:10:52
    basically
  • 00:10:53
    my brain just froze for a second then a
  • 00:10:56
    student wrote four statements about
  • 00:10:58
    water water has a high specific heat
  • 00:11:00
    capacity which maintains the temperature
  • 00:11:02
    of water within cells
  • 00:11:07
    mammals rely on water having a
  • 00:11:09
    relatively low latent heat of
  • 00:11:10
    vaporization this is wrong
  • 00:11:12
    water has a higher latent heat of your
  • 00:11:14
    position okay so the second statement
  • 00:11:18
    needs to be wrong
  • 00:11:20
    next when native charge yarn is add to
  • 00:11:23
    water the dill plus charge on the
  • 00:11:24
    hydroiantum is attracted to that cool
  • 00:11:26
    this is basically chemistry
  • 00:11:28
    by the way I don't know why Cambridge
  • 00:11:30
    makes uh these routines
  • 00:11:33
    they're actually uh really bad like the
  • 00:11:38
    paper ones are like one you don't have
  • 00:11:40
    gaps between paper ones right it's
  • 00:11:41
    basically 15 16 17 in zone four as far
  • 00:11:44
    as I know it's really messed up anyway
  • 00:11:51
    three is fine one is also Fine By the
  • 00:11:54
    way because water does have a high
  • 00:11:56
    specific which maintains the temperature
  • 00:11:57
    of water within cells when surrounded by
  • 00:11:59
    water non-polar markers tend to be
  • 00:12:01
    pushed apart from one another
  • 00:12:04
    foreign
  • 00:12:09
    factor is actually number four when
  • 00:12:11
    surrounded by water
  • 00:12:14
    suppose we have water non-polar
  • 00:12:17
    molecules
  • 00:12:18
    tend to be pushed apart from no no no
  • 00:12:21
    basically when you have water
  • 00:12:22
    surrounding you
  • 00:12:24
    the nonpolar molecules basically think
  • 00:12:27
    about Tails phospholipid tails
  • 00:12:33
    they are not pushed away from each other
  • 00:12:35
    right in fact what happens is they are
  • 00:12:37
    pushed towards each other
  • 00:12:40
    do you get it so in fact it's not a way
  • 00:12:44
    Apple not a part but rather two towards
  • 00:12:46
    so B is uh correct since 4 is in fact
  • 00:12:50
    wrong
  • 00:12:51
    okay one fourth done moving on to 11.
  • 00:12:56
    typical enzymes are large globular
  • 00:12:58
    proteins with a specific tertiary shape
  • 00:13:01
    which molecular interactions are
  • 00:13:03
    directly involved in maintaining the
  • 00:13:04
    tertiary shape
  • 00:13:07
    okay so the Russia structure contains
  • 00:13:09
    three types of bonds hydrogen bonds
  • 00:13:11
    disulfate Bridges hydrophobic
  • 00:13:13
    interactions and ionic interactions the
  • 00:13:17
    fourth one is missing here but here all
  • 00:13:19
    three are correct so I'm gonna go with
  • 00:13:20
    11a 12 which statement of the maker
  • 00:13:23
    instrumental constant is the correct for
  • 00:13:24
    an enzyme with the low Affinity
  • 00:13:25
    basically having a low Affinity means
  • 00:13:27
    remember the lower the value of nickel
  • 00:13:29
    is maintained constant it is the
  • 00:13:31
    substrate concentration at which its
  • 00:13:33
    half corresponds to half the V Max so
  • 00:13:35
    the lower the lower the maker is
  • 00:13:37
    maintained constant the higher the
  • 00:13:38
    Affinity so since there is low Affinity
  • 00:13:40
    at the value of micro is maintain
  • 00:13:42
    constant will be high okay
  • 00:13:45
    and
  • 00:13:47
    um basically this means that V Max will
  • 00:13:50
    be reached
  • 00:13:51
    at a high substrate concentration so it
  • 00:13:54
    isn't that efficient or the Affinity
  • 00:13:57
    isn't that high so basically I am going
  • 00:13:58
    to show you uh an example it's basically
  • 00:14:01
    like this
  • 00:14:04
    suppose if this is V Max
  • 00:14:07
    half V Max is here
  • 00:14:13
    but on the other hand an enzyme like
  • 00:14:15
    this
  • 00:14:18
    check this
  • 00:14:22
    isn't the the pink came over here much
  • 00:14:25
    lower than that so we need a high
  • 00:14:27
    substrate concentration
  • 00:14:29
    to reach
  • 00:14:31
    V Max get it so it's basically low
  • 00:14:34
    Affinity means you need High substance
  • 00:14:36
    concentration and the value of KM is
  • 00:14:38
    high Affinity is actually proportion is
  • 00:14:40
    inversely proportional to the value of
  • 00:14:43
    km the lower the value of game the
  • 00:14:45
    higher the Affinity 13. long chain
  • 00:14:48
    saturated fatty acids change from soil
  • 00:14:49
    to liquid at higher temperatures
  • 00:14:50
    compared with short chain unsaturated
  • 00:14:53
    which fatty acids would be more likely
  • 00:14:55
    to form
  • 00:14:56
    triglycerides in mammals that live in
  • 00:14:59
    cold climates
  • 00:15:05
    Okay so
  • 00:15:07
    we want to form triglycerides
  • 00:15:16
    [Music]
  • 00:15:28
    [Music]
  • 00:15:30
    so what do we need to analyze here
  • 00:15:32
    actually
  • 00:15:35
    um
  • 00:15:38
    foreign
  • 00:15:42
    figure this out
  • 00:15:53
    which fatty acids would be more likely
  • 00:15:55
    to form triglycerides in mammals that
  • 00:15:57
    live in cold climates
  • 00:16:07
    so tragister is a combination of Three
  • 00:16:09
    fatty acids and glycerol essentially
  • 00:16:15
    foreign
  • 00:16:18
    climates
  • 00:16:22
    it needs the ability
  • 00:16:24
    to turn from solid to liquid or else it
  • 00:16:27
    can't form a trial cell visceral
  • 00:16:29
    triglyceride basically
  • 00:16:31
    so if we had long chain saturated fatty
  • 00:16:35
    acids they wouldn't turn to liquid since
  • 00:16:38
    the temperature would be too cold
  • 00:16:40
    that is exactly why we need short chain
  • 00:16:42
    unsaturated fatty acids in the cold
  • 00:16:44
    climate
  • 00:16:45
    okay that's why the answer is D 13 is d
  • 00:16:50
    so in warmer climates like in deserts
  • 00:16:53
    typically uh the animals would have long
  • 00:16:55
    chain saturated fatty acids okay
  • 00:16:58
    due to the ability to you know
  • 00:17:00
    turn from solid to liquid
  • 00:17:06
    and think about it if in a hot climate
  • 00:17:08
    an animal had short chain on unsaturated
  • 00:17:11
    fatty acids in hot climate all of them
  • 00:17:14
    would literally uh melt they would
  • 00:17:18
    always be in a liquid state so in a hot
  • 00:17:20
    climate long chain and saturated fatty
  • 00:17:23
    acids would be fine but in uh
  • 00:17:26
    at low temperatures
  • 00:17:28
    short chain and unstructured fatty acids
  • 00:17:30
    are better
  • 00:17:33
    interesting question
  • 00:17:37
    I still think I could analyze this
  • 00:17:39
    better if I do get a better explanation
  • 00:17:42
    I'll mention this in the comments
  • 00:17:45
    or please feel free to do so if you
  • 00:17:47
    could analyze it better
  • 00:17:55
    basically to four fatty acids to form
  • 00:17:58
    triglycerides they need to react with
  • 00:18:00
    you know a glycerol
  • 00:18:04
    to make the Ester Bond
  • 00:18:06
    okay
  • 00:18:10
    to make the extra Bond
  • 00:18:11
    [Music]
  • 00:18:12
    so for that yeah it does need to be in a
  • 00:18:15
    liquid state
  • 00:18:16
    it does need to be in a liquid state
  • 00:18:19
    so if it was a long chain saturated
  • 00:18:21
    fatty acid
  • 00:18:23
    it would remain solid and it might not
  • 00:18:24
    be able to react with the glycerol to
  • 00:18:26
    make
  • 00:18:27
    the Ester Bond okay that's why we went
  • 00:18:30
    with this
  • 00:18:31
    other culture itself so I shouldn't have
  • 00:18:34
    to keep the cells alive what is the
  • 00:18:35
    purpose of this salt solution
  • 00:18:36
    [Music]
  • 00:18:39
    honestly uh we want to make it ISO
  • 00:18:43
    osmotic so that
  • 00:18:45
    excess water does not leave the cell or
  • 00:18:47
    excess water does not enter the cell
  • 00:18:50
    and cause lysis so honestly it's just
  • 00:18:54
    to prevent the net movement of watering
  • 00:18:56
    to or out of the cells basically you can
  • 00:18:58
    never prevent diffusion it will always
  • 00:19:00
    keep on happening it's just that the net
  • 00:19:02
    movement will remain the same it's
  • 00:19:04
    called an ISO osmotic solution okay
  • 00:19:07
    isotonic
  • 00:19:08
    not hyper or hypotonic the following are
  • 00:19:11
    all processes that allow movement into
  • 00:19:13
    cells okay which process is required to
  • 00:19:16
    be this requires ATP this requires ATP
  • 00:19:17
    okay one and two facilated diffusion is
  • 00:19:20
    a passive process but it requires a
  • 00:19:22
    carrier which features are required to
  • 00:19:24
    allow for efficient diffusion large
  • 00:19:26
    surface area true
  • 00:19:27
    short diffusion pathway true constant
  • 00:19:30
    diffusion gradient of course answer is a
  • 00:19:32
    remember we need a large surface area to
  • 00:19:34
    volume ratio we need high temperature we
  • 00:19:36
    need a short diffusion pathway the
  • 00:19:38
    thinner it is like alveoli right the
  • 00:19:40
    easier it is to diffuse and yeah we need
  • 00:19:43
    a constant diffusion gradient okay what
  • 00:19:45
    is the role of mitosis
  • 00:19:47
    growth of organisms reposals production
  • 00:19:50
    of genetically different cells
  • 00:19:51
    replacement of cancerous tissue this is
  • 00:19:54
    mainly from the coursework chapter 5.
  • 00:19:57
    so honestly
  • 00:19:59
    um it should be genetically identical
  • 00:20:02
    this is not really this is not really a
  • 00:20:06
    role okay replacement of cancerous
  • 00:20:08
    tissue
  • 00:20:09
    the answer is growth it's required for
  • 00:20:12
    asexual reproduction growth I can show
  • 00:20:14
    you actually I can show you
  • 00:20:16
    here you go chapter five do I have it
  • 00:20:19
    here I don't think so wait
  • 00:20:23
    yeah growth replacement of damaged cells
  • 00:20:26
    or dead cells and repair of tissues by
  • 00:20:28
    cell replacement but you guys need to
  • 00:20:31
    understand that Reaper can also be done
  • 00:20:32
    by production of proteins asexual
  • 00:20:34
    reproduction and anything else no these
  • 00:20:37
    three
  • 00:20:38
    mileage history and also in immune
  • 00:20:40
    response sorry so remember these three
  • 00:20:43
    and everything else should be fine
  • 00:20:44
    logically
  • 00:20:47
    by the way guys if you're just looking
  • 00:20:49
    at bad videos I have chemistry and
  • 00:20:51
    physics solved as well
  • 00:20:53
    so if you want to check those out I'm
  • 00:20:55
    going to link the card above so just
  • 00:20:56
    check that out okay it's going to be
  • 00:20:58
    linked up here
  • 00:21:00
    like I I've seen a lot of my students
  • 00:21:03
    reply in the comment sections that they
  • 00:21:05
    don't even they think this channel is
  • 00:21:06
    for Bio only or something but they are
  • 00:21:09
    math physics and chemistry videos if you
  • 00:21:10
    need those all right
  • 00:21:12
    anyway uh repair of sales by replacement
  • 00:21:14
    would have been a better option but
  • 00:21:16
    there is no replacement
  • 00:21:18
    and it should be production genetical
  • 00:21:20
    identical so so a is fine okay 18.
  • 00:21:24
    telomeres prevent the loss of genes from
  • 00:21:26
    the ends of chromosomes during DNA
  • 00:21:28
    replication but they become shorter each
  • 00:21:30
    time they are copied in cancer cells and
  • 00:21:32
    stem cells the telomeres remain the same
  • 00:21:34
    length basically telomerase prevents the
  • 00:21:36
    shortening
  • 00:21:38
    which statement is correct for all human
  • 00:21:39
    cells if telomeres become too short
  • 00:21:43
    a cell may stop dividing this is 100
  • 00:21:45
    fine
  • 00:21:47
    basically the short ring of telomeres
  • 00:21:49
    causes aging and that prevents the
  • 00:21:52
    mitosis of cells and that causes death
  • 00:21:55
    over time adding telomeres could
  • 00:21:57
    increase the rate of Aging wrong it
  • 00:21:59
    would be decreased telomeres are
  • 00:22:00
    repaired by the enzyme telomerase tailor
  • 00:22:03
    must prevent all damages occurring to
  • 00:22:04
    DNA molecules this is wrong mutations
  • 00:22:06
    can still occur guys the nucleus of a
  • 00:22:09
    mass body cell in G1 phase of the cell
  • 00:22:11
    cycle has 1.2 into 10 to the power minus
  • 00:22:14
    12 grams of DNA by the way uh
  • 00:22:18
    let me know if you're fine with the
  • 00:22:19
    pacing of the video if you want slower
  • 00:22:21
    explanations I'll slow down next time
  • 00:22:25
    the nucleus of a mouse body cell in G1
  • 00:22:27
    phase of the cell cycle has 1.2 into 10
  • 00:22:29
    per minus 12 grams of DNA what will be
  • 00:22:31
    the mass of DNA in the nucleus of the
  • 00:22:33
    cell the end of this phase and at the
  • 00:22:35
    end of the G2 phase
  • 00:22:37
    basically in the G1 phase synthesis has
  • 00:22:40
    not occurred in this phase synthesis
  • 00:22:42
    will occur and basically da will become
  • 00:22:44
    double of its initial value and at the
  • 00:22:47
    end of G2 honestly it should remain the
  • 00:22:49
    same because cytokinesis has not
  • 00:22:52
    occurred yet so it will be double which
  • 00:22:54
    is 2.4 into 10 per minus 12 and it will
  • 00:22:56
    persist
  • 00:22:57
    20 what are crystalline Pro face the
  • 00:23:00
    nucleolus disappears I agree
  • 00:23:02
    fragmentation of the nuclear envelope
  • 00:23:05
    I agree as well stained chromosomes
  • 00:23:08
    become visible true although it is the
  • 00:23:09
    most visible at metaphase centrums
  • 00:23:12
    replicate this is wrong
  • 00:23:13
    this actually happens before profits
  • 00:23:16
    begins check this check this way up
  • 00:23:22
    um here you go
  • 00:23:23
    so the central centrosomes or centrals
  • 00:23:26
    have already been replicated during the
  • 00:23:28
    S phase of the cell cycle clear
  • 00:23:32
    great
  • 00:23:36
    so four is wrong that should be
  • 00:23:39
    we're done with half
  • 00:23:41
    which statement describes the structure
  • 00:23:42
    of ATP
  • 00:23:44
    so ATP adenosine triphosphate
  • 00:23:48
    okay
  • 00:23:50
    adenosine triphosphere what is ATP it is
  • 00:23:53
    mainly an RNA molecule
  • 00:23:56
    okay
  • 00:23:59
    because there's it's a rhyme it's rival
  • 00:24:02
    sugar basically adenocide
  • 00:24:05
    if you guys want to see the structure
  • 00:24:07
    because it's not deoxyribose it's
  • 00:24:09
    actually
  • 00:24:10
    just
  • 00:24:13
    um Rivals wait up
  • 00:24:16
    we have adenine arrival sugar not
  • 00:24:19
    deoxyribose
  • 00:24:20
    adenine plus variables this is adenosine
  • 00:24:22
    and if you add three phosphate groups
  • 00:24:25
    you're gonna get adenosine try phosphate
  • 00:24:28
    great
  • 00:24:30
    so so an RNA nucleotide already contains
  • 00:24:35
    one phosphate
  • 00:24:36
    Okay so
  • 00:24:42
    this is the base
  • 00:24:44
    rivals
  • 00:24:45
    so if you this is the RNA included now
  • 00:24:48
    if you add two more phosphates
  • 00:24:50
    you're gonna get the ATP molecule so 21
  • 00:24:52
    is in fact C it should not be three
  • 00:24:55
    extra River Basin great guys so this we
  • 00:24:58
    use this drug to treat tuberculosis
  • 00:25:00
    tuberculosis is not really common
  • 00:25:04
    um in the west it's much more common in
  • 00:25:06
    Bangladesh
  • 00:25:08
    where I'm from and in Southeast Asia so
  • 00:25:11
    we mainly use four drugs to treat
  • 00:25:13
    tuberculosis as soon as it
  • 00:25:17
    price and it might lithium butyl and
  • 00:25:19
    Reformation
  • 00:25:21
    it's a fixed dose regiment
  • 00:25:26
    so refund person is an antibiotic used
  • 00:25:28
    to treat tuberculosis it works by
  • 00:25:30
    inhibiting RNA polymers in the bacteria
  • 00:25:33
    basically I have to remember this so the
  • 00:25:35
    ways are for r with ambition X on RNA
  • 00:25:39
    polymers irony polymers is actually in
  • 00:25:41
    charge of transcription or mRNA
  • 00:25:43
    production so which processes are
  • 00:25:45
    directly inhibited by this antibiotic
  • 00:25:48
    basically DNA replication is not
  • 00:25:50
    inhibited because because guys that's
  • 00:25:53
    DNA polymers is responsible for that it
  • 00:25:56
    actually inhibits the enzyme synthesis
  • 00:25:57
    because enzyme is a protein so this
  • 00:25:59
    cannot produce the MRNA so the enzyme
  • 00:26:01
    cannot be produced okay so 2 is correct
  • 00:26:04
    ATP synthesis
  • 00:26:06
    honestly ATP synthesis
  • 00:26:09
    does not depend on the on protein
  • 00:26:12
    production because in adenosine
  • 00:26:14
    triphosphate we have phosphates bases
  • 00:26:16
    and ribose that's monosaccharide so we
  • 00:26:18
    don't really need protein so three is
  • 00:26:20
    wrong it's actually only two
  • 00:26:22
    so 20
  • 00:26:24
    3 the table shows the DNA triplet codes
  • 00:26:26
    for some amino acids the base sequence
  • 00:26:29
    of the on the template DNA strand coding
  • 00:26:31
    for part of the wallpaper that is shown
  • 00:26:33
    two mutations occur in the sequence
  • 00:26:35
    during DNA replication which mutated
  • 00:26:37
    template DNA strand would result in a
  • 00:26:39
    shorter permutent so we basically need a
  • 00:26:41
    stop codon guys we need ATC
  • 00:26:44
    ATC okay
  • 00:27:01
    foreign
  • 00:27:24
    this is a DNA
  • 00:27:27
    foreign
  • 00:27:37
    all right
  • 00:27:40
    so here we have 87 is that it is that
  • 00:27:43
    the MC like I was looking for a harder
  • 00:27:44
    thing basically we needed to identify
  • 00:27:46
    the stop codon that's it this is
  • 00:27:49
    literally nothing else so there'll be
  • 00:27:51
    premature termination of the protein
  • 00:27:53
    chain this won't be uh trans uh this
  • 00:27:56
    won't be transcribed okay
  • 00:27:58
    or this won't be translated that section
  • 00:28:00
    so the features uh present in transfer
  • 00:28:04
    tissues are listed I honestly hate
  • 00:28:06
    chapter seven
  • 00:28:06
    [Music]
  • 00:28:09
    uh it's really lame chapter some of the
  • 00:28:11
    features present in transfer tissues are
  • 00:28:13
    listed
  • 00:28:14
    which features are present in xylem
  • 00:28:16
    vessels okay great
  • 00:28:18
    so xylem is actually lignified
  • 00:28:21
    and xylem has spits but it's since it's
  • 00:28:23
    dead it has no cytoplasm it has no
  • 00:28:26
    mitochondria and it has no plasmodes
  • 00:28:28
    Mata so it should be one and four only
  • 00:28:30
    okay 24 is C
  • 00:28:32
    25 really important question common
  • 00:28:34
    question guys you need to be a master at
  • 00:28:36
    this okay so we have a leaf stem root
  • 00:28:45
    so guys remember
  • 00:28:48
    for the leaf
  • 00:28:50
    for the leaf in the mid grip the the one
  • 00:28:52
    pointing upwards okay
  • 00:28:55
    basically we need to identify xylem and
  • 00:28:58
    phloem
  • 00:28:59
    let me try and fix xylem and phloem okay
  • 00:29:02
    so in the leaf the one pointing upwards
  • 00:29:04
    is xylem and this one is phloem
  • 00:29:09
    okay the one in the upper section is
  • 00:29:11
    alum the one in the lower section is
  • 00:29:13
    actually phloem
  • 00:29:15
    next
  • 00:29:18
    in the root the xylem is actually the
  • 00:29:21
    one inside so four is xylem and the one
  • 00:29:24
    pointing outside is
  • 00:29:26
    flow M and the root is the easiest to
  • 00:29:28
    remember honestly this star-shaped
  • 00:29:31
    region okay
  • 00:29:32
    this is your xylem and this part is the
  • 00:29:34
    fluid
  • 00:29:36
    so according to my analysis
  • 00:29:40
    yeah it should honestly be B I'm
  • 00:29:42
    guessing because one four six okay so
  • 00:29:44
    you need to remember this don't forget
  • 00:29:46
    this you'll be asked to drop land
  • 00:29:47
    diagrams in practicals I think you've
  • 00:29:50
    already you're already done with
  • 00:29:51
    practicals I'm assuming right
  • 00:29:53
    okay 26 which molecules from hydrogen
  • 00:29:55
    bonds with water Gene transfer
  • 00:29:57
    transpiration okay cellulose in this
  • 00:30:00
    island wow yes
  • 00:30:03
    um this is true sea burn in the xylem
  • 00:30:05
    wall
  • 00:30:06
    other water molecules in this island
  • 00:30:09
    so basically the xylem the sales in
  • 00:30:12
    xylem and the H2 in the xylem form water
  • 00:30:14
    form hydrogen bonds but two is strong
  • 00:30:16
    this is actually present in the
  • 00:30:18
    endodermis you know the casparian strip
  • 00:30:20
    so it's one and three only twin six is C
  • 00:30:23
    27 some plant species can take up heavy
  • 00:30:26
    metal contaminants that are dissolved in
  • 00:30:28
    soil water and then transport them
  • 00:30:29
    within the plant within plant cells the
  • 00:30:31
    heavy metals accumulate mainly in the
  • 00:30:33
    vacuum with suggestions about the
  • 00:30:35
    transport and accumulation of heavy
  • 00:30:36
    metals are valid after initial entry
  • 00:30:38
    into the roots some of the heavy metals
  • 00:30:40
    can pass through the tonoplast to be
  • 00:30:42
    stored in the vacuole of cells in the
  • 00:30:45
    cortex
  • 00:30:49
    I agree with this honestly I do agree
  • 00:30:51
    with this because they'll be stored in
  • 00:30:53
    the vacuum
  • 00:30:54
    the tonoplast is basically the membrane
  • 00:30:56
    of the vehicle the hair Metals take an
  • 00:30:58
    apple plus okay their two Pathways apple
  • 00:31:00
    plus and C plus apple plus is true the
  • 00:31:02
    cell walls and seam test is the
  • 00:31:04
    intracellular root uh through the plasma
  • 00:31:07
    does matter the heavy metals take an
  • 00:31:09
    apoplastic path with the xylem but at
  • 00:31:11
    the end the term is they must take a
  • 00:31:12
    simplistic battery this is true because
  • 00:31:14
    it's blocked then determines by the
  • 00:31:16
    Caspian strip one and two are fine okay
  • 00:31:19
    so the answer should be a but I'm still
  • 00:31:21
    checking three and four the rate of
  • 00:31:22
    accumulation of heavy metals in the leaf
  • 00:31:24
    cells will be faster at night wrong
  • 00:31:26
    photosynthesis actually increases the
  • 00:31:28
    transformation stream four the presence
  • 00:31:30
    of heavy metals causes transmission
  • 00:31:31
    stream to slow down and
  • 00:31:34
    reduce the rate of transformation
  • 00:31:40
    there is actually no data based on this
  • 00:31:42
    so we can't actually see okay
  • 00:31:44
    twin seven is a
  • 00:31:46
    what is the correct route for the
  • 00:31:47
    movement of water from cell to cell in
  • 00:31:49
    the Upper Plus pathway
  • 00:31:50
    okay so Apple blast
  • 00:31:52
    is cell wall root
  • 00:31:56
    okay silver
  • 00:31:57
    so basically it cannot move through the
  • 00:32:00
    Caspian strip it does not move to the
  • 00:32:03
    plasma test Master it basically
  • 00:32:10
    uh
  • 00:32:12
    moves through
  • 00:32:14
    intercellular spaces
  • 00:32:17
    so I maybe I worded something wrong
  • 00:32:21
    here guys maybe I said intercellular by
  • 00:32:24
    mistake
  • 00:32:26
    uh over here
  • 00:32:30
    I went intra I I don't remember what I
  • 00:32:32
    said basically
  • 00:32:34
    the heavy metals take an apoplastic
  • 00:32:36
    pathway in the xylem but at the
  • 00:32:38
    endothermics must take a seam Plus
  • 00:32:40
    Battery so apoplectic pathway
  • 00:32:45
    is actually the movement through the
  • 00:32:48
    cell walls it's between cells
  • 00:32:51
    essentially
  • 00:32:52
    between two cells through the cellos the
  • 00:32:56
    simplest pathways through the
  • 00:32:58
    plasmodesmata it's an intra cellular
  • 00:33:02
    path so this is intra and this is inter
  • 00:33:04
    in terms between cells intra means
  • 00:33:07
    through or within cells okay so
  • 00:33:09
    intercellular spaces is fine for apple
  • 00:33:12
    plus it cannot move thread just in cell
  • 00:33:14
    surface membranes okay so more
  • 00:33:17
    clarification on this over here check
  • 00:33:18
    this
  • 00:33:19
    chapter 7 just check this diagram
  • 00:33:23
    ever blast water enter cell wall moves
  • 00:33:25
    through the cell wall through the
  • 00:33:28
    interstellar spaces water May directly
  • 00:33:31
    move from server to server water enters
  • 00:33:34
    the cytoplasm by osmosis by the partial
  • 00:33:36
    permute cell surface membrane it moves
  • 00:33:38
    into the vacuole by the tonoplast water
  • 00:33:40
    may move from cell to cell through
  • 00:33:42
    plasmodesmata water may move from cell
  • 00:33:44
    to cells through adjacent cell surface
  • 00:33:46
    membranes as well so you need to
  • 00:33:47
    memorize these eight points okay then
  • 00:33:49
    everything else will fall into place
  • 00:33:50
    understood
  • 00:33:53
    great which shows the correct sequence
  • 00:33:56
    for the moment of sucrose into fluency
  • 00:33:59
    tubes okay
  • 00:34:01
    so mainly guys uh we pump h plus
  • 00:34:04
    actively from the component cell into
  • 00:34:06
    the cell wall
  • 00:34:09
    okay
  • 00:34:11
    at first this is the fluency tube this
  • 00:34:14
    is the companion cell this is the cell
  • 00:34:16
    wall the pump h plus actively into the
  • 00:34:18
    cell wall from the component so this is
  • 00:34:20
    what happens at first
  • 00:34:26
    okay so active transport of protons out
  • 00:34:29
    of the not into
  • 00:34:31
    [Music]
  • 00:34:33
    co-transfer wrong diffusion wrong Active
  • 00:34:35
    Transfer protons into the component's
  • 00:34:37
    cell wrong it should be out of density
  • 00:34:40
    clearly
  • 00:34:43
    [Music]
  • 00:34:47
    next
  • 00:34:49
    co-transport of protons I think let's
  • 00:34:52
    check the next one what happens next is
  • 00:34:54
    basically uh an h plus gradient is built
  • 00:34:57
    up it will move
  • 00:34:58
    back into the component cell
  • 00:35:02
    passively through a co-transporter that
  • 00:35:04
    also carries a sucrose with it okay this
  • 00:35:06
    is a passive process this is fine and
  • 00:35:08
    then sucrose will diffuse from the
  • 00:35:10
    compensil to the fluency through the
  • 00:35:13
    plasma this one okay D is correct what
  • 00:35:15
    occurs during ventricular system in a
  • 00:35:17
    mammalian Hearts okay ventricular system
  • 00:35:20
    basically if you look at the diagram
  • 00:35:22
    wait let me bring the diagram from
  • 00:35:24
    variant 1 1.
  • 00:35:28
    [Music]
  • 00:35:31
    go
  • 00:35:32
    [Music]
  • 00:35:40
    [Music]
  • 00:35:45
    okay so they're saying that
  • 00:35:48
    aortic pressure increases
  • 00:35:51
    obviously
  • 00:35:55
    doing at your sister
  • 00:35:58
    is it wait what sister
  • 00:36:00
    ventricular I mean erotic obviously
  • 00:36:03
    aortic pressure will increase
  • 00:36:05
    because this is when ventricular sister
  • 00:36:07
    is occurring
  • 00:36:11
    so the aortic pressure increases
  • 00:36:15
    that's the red line
  • 00:36:16
    okay the red line electric pressure
  • 00:36:18
    increases then they said that the atrial
  • 00:36:21
    pressure does not change but look guys
  • 00:36:24
    look at the yellow line the atrial
  • 00:36:26
    pressure slightly changes okay doing
  • 00:36:28
    vertical system it does change it
  • 00:36:30
    doesn't remain stationary so two is
  • 00:36:32
    actually wrong atrial pressure does
  • 00:36:34
    change two is wrong
  • 00:36:36
    if ventricular pressure increases
  • 00:36:38
    obviously look at the Blue Line
  • 00:36:40
    ventricular pressure increases by a lot
  • 00:36:42
    okay so this is red this is right we're
  • 00:36:44
    going to go with 1 and 330 is B
  • 00:36:47
    great
  • 00:36:50
    a major vein I was talking about this in
  • 00:36:52
    variant one one as well so what about
  • 00:36:55
    the vein guys let's talk about the vein
  • 00:36:58
    essentially the vein
  • 00:37:00
    basically what about the Lumen the Lumen
  • 00:37:02
    is actually pretty big for a win
  • 00:37:05
    check this
  • 00:37:08
    the Lumen is pretty big
  • 00:37:11
    it has a technique intima it also has a
  • 00:37:13
    Tunica Media the middle layer
  • 00:37:17
    it's very thin contains some smooth
  • 00:37:19
    muscle ingesting fibers
  • 00:37:21
    he doesn't have collagen really
  • 00:37:25
    unlike arteries and the outer layer
  • 00:37:27
    contains mostly collagen okay
  • 00:37:31
    it is a relatively large Snowman
  • 00:37:34
    so
  • 00:37:39
    which plan diagram represents the
  • 00:37:42
    tissues in the major vein so the
  • 00:37:44
    endodermis has to be very thin
  • 00:37:48
    all of it is like that
  • 00:37:51
    and what about the other ones look at
  • 00:37:54
    the plan diagram over here basically it
  • 00:37:58
    was very thick in the artery over here
  • 00:37:59
    right they were of equal thickness and
  • 00:38:03
    the endothermist was very thin but here
  • 00:38:06
    look
  • 00:38:07
    you have a very thin inner layer very
  • 00:38:10
    thin middle layer but the outer layer is
  • 00:38:12
    very thick okay that's what you need to
  • 00:38:14
    pay attention to
  • 00:38:16
    the outer layer will be very thick as a
  • 00:38:19
    result 31
  • 00:38:21
    the answer is d
  • 00:38:25
    you have a one cell thick inner layer
  • 00:38:27
    you have very thin middle layer this
  • 00:38:30
    outer layer is very thick
  • 00:38:31
    [Music]
  • 00:38:32
    okay
  • 00:38:38
    so guys uh what's the difference between
  • 00:38:42
    A and D then it's just that a has a much
  • 00:38:48
    you know it has a much smaller
  • 00:38:51
    or narrower Lumen but D has a great
  • 00:38:54
    lumens so it was between D and C anyway
  • 00:38:56
    because these were the lumens of
  • 00:38:57
    arteries
  • 00:39:01
    I'm going to clarify again
  • 00:39:04
    so y d over C
  • 00:39:07
    in 31 why do you ever see
  • 00:39:10
    the diagram over here is in that um
  • 00:39:12
    great actually
  • 00:39:14
    we have a large lumen
  • 00:39:16
    the middle layer will be very thin and
  • 00:39:19
    outer layer is mostly collagen fibers
  • 00:39:21
    and we also have an external layer
  • 00:39:24
    [Music]
  • 00:39:26
    I'll show you what I mean by that
  • 00:39:29
    but let me see if I can get a better
  • 00:39:31
    photo
  • 00:39:33
    this is a bit hard to read
  • 00:39:37
    but yeah okay so
  • 00:39:39
    mainly by elimination A and B are gone
  • 00:39:41
    it's between C and D
  • 00:39:44
    in CND we only see
  • 00:39:53
    wait let me show you
  • 00:39:58
    plan diagram of vein
  • 00:40:01
    [Music]
  • 00:40:04
    foreign
  • 00:40:19
    [Music]
  • 00:40:23
    they have the same photo here
  • 00:40:26
    [Music]
  • 00:40:32
    it's like this basically
  • 00:40:35
    this is the plan diagram for vain
  • 00:40:39
    the intima is very small then you have
  • 00:40:41
    the media
  • 00:40:46
    [Music]
  • 00:40:50
    um wait
  • 00:40:54
    [Music]
  • 00:40:57
    I think
  • 00:40:58
    [Music]
  • 00:41:00
    copy
  • 00:41:03
    let me zoom into this
  • 00:41:06
    [Music]
  • 00:41:14
    yeah so we have intimate over here
  • 00:41:18
    then we have media
  • 00:41:20
    then adventitia
  • 00:41:24
    basically the main difference over here
  • 00:41:26
    is check this
  • 00:41:29
    um
  • 00:41:30
    the middle there for archery is is very
  • 00:41:33
    thick but the middle there
  • 00:41:38
    in venules or veins is much
  • 00:41:41
    Less in thickness than the outer layer
  • 00:41:44
    which contains collagen fibers
  • 00:41:49
    so was there a plane diagram of the
  • 00:41:52
    arterial over here let me see let me
  • 00:41:54
    check
  • 00:41:56
    I'm in the venue
  • 00:42:01
    [Music]
  • 00:42:07
    [Music]
  • 00:42:10
    so this seems better right the one on
  • 00:42:12
    the right
  • 00:42:13
    I guess this is fine
  • 00:42:20
    but here basically I wanted to highlight
  • 00:42:25
    that in the course book they actually
  • 00:42:27
    showed us that the outer layer was uh
  • 00:42:29
    much thicker
  • 00:42:31
    okay but it actually varies from vein to
  • 00:42:33
    pin this is a specific vein this is a
  • 00:42:35
    small vein like in larger veins it does
  • 00:42:38
    vary
  • 00:42:39
    in larger events it's like this you will
  • 00:42:41
    usually see this diagram this plant
  • 00:42:43
    diagram over here okay
  • 00:42:45
    so this is the difference between them
  • 00:42:51
    all right
  • 00:42:53
    [Music]
  • 00:42:54
    so according to that
  • 00:42:56
    you have to go through this because the
  • 00:42:58
    problem with C was it only had look one
  • 00:43:01
    and two layers where's the last layer
  • 00:43:02
    that's the problem with C but we know
  • 00:43:04
    that veins have three layers so that's
  • 00:43:06
    that okay you guys don't need any other
  • 00:43:07
    details so large Lumen and three layers
  • 00:43:09
    that's all
  • 00:43:12
    three two the diagram shows the presence
  • 00:43:13
    shows the pressure changes in various
  • 00:43:16
    structures of the left side of the heart
  • 00:43:18
    doing the cardiac cycle at the end of
  • 00:43:20
    which period is The ventricle full of
  • 00:43:21
    blood okay throw back to this
  • 00:43:24
    um
  • 00:43:24
    this picture check this
  • 00:43:29
    there was another picture wait not bad
  • 00:43:35
    there was another picture in brand one
  • 00:43:40
    here you go
  • 00:43:41
    [Music]
  • 00:43:42
    this can give you more details
  • 00:43:49
    so honestly
  • 00:43:51
    at 100 millisecond over here
  • 00:43:54
    the Atria ventricular valve closes and
  • 00:43:56
    the
  • 00:44:00
    ventricular contraction just begins at
  • 00:44:03
    this point
  • 00:44:04
    and here the aortic valve opens so The
  • 00:44:06
    ventricle is about to empty
  • 00:44:09
    that's basically the ventricular
  • 00:44:10
    ejection okay
  • 00:44:12
    where this one opens afterwards so they
  • 00:44:17
    asked us here where is the
  • 00:44:19
    ventricle full of blood okay so that's
  • 00:44:22
    basically doing ventricular feeling
  • 00:44:25
    look at doing ventricular feeling
  • 00:44:28
    this portion
  • 00:44:31
    so honestly
  • 00:44:35
    this is when the Atria is Atria when the
  • 00:44:38
    atrium or Atria are Contracting really
  • 00:44:40
    okay so according to this we know that
  • 00:44:43
    in B it can be possible
  • 00:44:45
    because the Atria ventricular valve at
  • 00:44:48
    this point over here the heter
  • 00:44:50
    ventricular valve opens I mean the
  • 00:44:53
    uh
  • 00:44:54
    at this point the AV valve
  • 00:44:58
    closes and here the aortic valve opens
  • 00:45:03
    so after this point all blood rushes out
  • 00:45:06
    of The ventricle so The ventricle
  • 00:45:07
    becomes empty starting from B so just
  • 00:45:10
    before the ventricle becomes empty at
  • 00:45:12
    this point The ventricle is full okay
  • 00:45:14
    because look it's a closed chamber
  • 00:45:17
    so point a actually refers to this
  • 00:45:19
    section of this diagram
  • 00:45:25
    this part basically both are closed so
  • 00:45:27
    The ventricle is full right after this
  • 00:45:28
    this is basically after a trial
  • 00:45:30
    contraction therefore right after this
  • 00:45:32
    Blood exits The ventricle okay
  • 00:45:34
    hopefully that makes sense
  • 00:45:38
    sensory which description of movement of
  • 00:45:40
    substances during tissue fluid formation
  • 00:45:42
    is great
  • 00:45:45
    low hydrostatic pressure forces
  • 00:45:47
    substances out of the capillary at the
  • 00:45:49
    arterial
  • 00:45:50
    no not really at that end the
  • 00:45:53
    hydrostatic pressure is higher so that
  • 00:45:55
    allows
  • 00:45:57
    it to exit so a is wrong
  • 00:45:59
    tissue fluid moves back into the finial
  • 00:46:01
    due to a net hydrostatic pressure change
  • 00:46:03
    in the capillary
  • 00:46:05
    foreign
  • 00:46:17
    pressure inside the Capri
  • 00:46:24
    this is correct C is better not b
  • 00:46:29
    so it's mainly due to the lower water
  • 00:46:31
    potential as well as the low hydrostatic
  • 00:46:33
    pressure inside the capillary
  • 00:46:35
    okay this is very important for you guys
  • 00:46:39
    basically
  • 00:46:41
    in the capital bit what happens in the
  • 00:46:43
    arterial end we actually end up losing
  • 00:46:45
    plasma
  • 00:46:48
    okay so it is mainly due to the
  • 00:46:50
    High hydrostatic pressure and
  • 00:46:55
    the lowest amount of solids in the blood
  • 00:46:57
    and in the venison
  • 00:46:59
    it is mainly due to the high solid
  • 00:47:01
    concentration that is the low osmolarity
  • 00:47:05
    which is the highest solid concentration
  • 00:47:07
    and the hydrostatic pressure gradient is
  • 00:47:10
    still pointing outside
  • 00:47:12
    okay it's always outside it's just that
  • 00:47:14
    the hydrostatic pressure grain is much
  • 00:47:16
    higher at the arteriant
  • 00:47:17
    but the solid concentration grade is
  • 00:47:19
    higher at this end okay
  • 00:47:21
    got it
  • 00:47:27
    so it's actually not the net hydrostatic
  • 00:47:29
    pressure that's from
  • 00:47:31
    is it a low hydrostatic pressure and due
  • 00:47:33
    to the low water potential
  • 00:47:37
    this is wrong it should be a low it
  • 00:47:39
    should be high hydrostatic pressure
  • 00:47:41
    which row shows the change in
  • 00:47:42
    consideration of some substances in RBC
  • 00:47:44
    and carbon dioxide decreases from active
  • 00:47:46
    cells into the RBC okay so Carbonic
  • 00:47:49
    anhydrase is an enzyme come on guys this
  • 00:47:51
    is a trick question there will be no
  • 00:47:52
    change
  • 00:47:53
    so Carbonic anhydrous catalyzes this
  • 00:47:56
    reaction it produces h2co3 okay
  • 00:47:59
    so h2co3 breaks down to form hco3 minus
  • 00:48:02
    and forms h plus so bicarbon trans
  • 00:48:05
    actually
  • 00:48:06
    increases that is why I'm going to go
  • 00:48:08
    with d this is wrong hydrogen ions also
  • 00:48:11
    increases okay
  • 00:48:12
    last six which statements are the human
  • 00:48:15
    gas exchange system are correct
  • 00:48:18
    the absence of cartilage in small
  • 00:48:20
    bronchules allow them to expand
  • 00:48:22
    cartilage is present only in bronchi and
  • 00:48:25
    trachea
  • 00:48:27
    so this looks good this allows uh them
  • 00:48:31
    to constrict and expand the walls of the
  • 00:48:34
    alveoli are made up of squamous
  • 00:48:35
    epithelium two is wrong two is wrong two
  • 00:48:38
    is wrong alve is a secret substance
  • 00:48:40
    which uses surface tension surfactant so
  • 00:48:42
    one and three are great the track and
  • 00:48:45
    bronchitis suffered by Rings no see
  • 00:48:47
    track is suffered by c-shaped rings
  • 00:48:50
    and bronchers are by like blocks of
  • 00:48:53
    cartilage four types of cells in the gas
  • 00:48:55
    exchange system are listed below
  • 00:48:59
    smooth processor Okay so
  • 00:49:03
    let's see
  • 00:49:05
    which takes show the specialized
  • 00:49:07
    features of three types of these cells
  • 00:49:09
    let's see
  • 00:49:13
    [Music]
  • 00:49:17
    so one cell is unique it has a lot of
  • 00:49:19
    endoplasmic reticulum and many Golgi
  • 00:49:21
    bodies
  • 00:49:24
    so clearly
  • 00:49:26
    this type 3 okay which one is it out of
  • 00:49:30
    here that's the determining Factor
  • 00:49:31
    clearly goblet cell because it needs it
  • 00:49:34
    is a secret mucus mucine right that's
  • 00:49:36
    why it needs Golgi body for packing and
  • 00:49:38
    endoplasmic reticulum for producing the
  • 00:49:40
    protein that is why I'm gonna go with C
  • 00:49:41
    that's the way to answer this nothing
  • 00:49:43
    else all the others are the same more or
  • 00:49:45
    less
  • 00:49:46
    why is it difficult to control the speed
  • 00:49:47
    of TB
  • 00:49:49
    so TB is mainly spread by droplets okay
  • 00:49:52
    and honestly tuberculosis is a dormant
  • 00:49:55
    disease
  • 00:49:57
    it stays unnoticed from many years
  • 00:50:00
    Global air travel for Commerce and
  • 00:50:02
    tourism has increased okay this actually
  • 00:50:04
    increases it by the droplet transmission
  • 00:50:07
    so this is correct the pattern that
  • 00:50:10
    causes tuberculosis has evolved
  • 00:50:11
    resistance this is true the bacteria
  • 00:50:14
    that causes tuberculosis shows the great
  • 00:50:16
    antigenic viability civil unrest and
  • 00:50:19
    poverty result in overcrowded living
  • 00:50:21
    conditions overcrowding it should be one
  • 00:50:23
    two and four
  • 00:50:24
    okay why not three though
  • 00:50:30
    so antigenic variability
  • 00:50:34
    it's not really a factor but even if
  • 00:50:36
    there was entertaining variability that
  • 00:50:38
    would cause problems in
  • 00:50:41
    uh treatment rather than Spread spread
  • 00:50:44
    is the key word so here we're looking
  • 00:50:45
    for methods of spread mainly
  • 00:50:47
    last few ones rabies is a viral disease
  • 00:50:50
    which can be spread to humans by vitrome
  • 00:50:53
    infected animal one method of treatment
  • 00:50:55
    is to inject the patient with antibodies
  • 00:50:57
    specific to the rabies wires which
  • 00:50:59
    statement about this treatment required
  • 00:51:00
    the patient will have natural passive so
  • 00:51:04
    it's actually passive immunity but it's
  • 00:51:06
    artificial not natural because it hasn't
  • 00:51:09
    passed through placenta or breast milk
  • 00:51:11
    so one is actually wrong it's between C
  • 00:51:14
    and D 38 is written C and D
  • 00:51:18
    danger to antibodies will be broken down
  • 00:51:20
    by the patient this is true over time it
  • 00:51:22
    will the patient's memory cells will be
  • 00:51:24
    able to produce this antibody wrong
  • 00:51:26
    artificial antibody artificial
  • 00:51:28
    protection or immunity does not help in
  • 00:51:31
    producing vessels it will last for a
  • 00:51:33
    short time okay it is short-lived so the
  • 00:51:35
    answer is 2 and 4 38D last two okay for
  • 00:51:39
    39 a person's blood group is determined
  • 00:51:41
    the antigens present on the red blood
  • 00:51:43
    cells the table shows the antigens and
  • 00:51:44
    antibodies in the blood of people with
  • 00:51:47
    different blood groups okay so we know
  • 00:51:50
    that a B has no antibodies o has both
  • 00:51:53
    antibodies B has NTA and a has NTB
  • 00:51:56
    antibodies and the other antigens during
  • 00:52:00
    a blood transfusion it is essentially
  • 00:52:01
    the person who receives the blood does
  • 00:52:03
    not have antibodies to the donors but
  • 00:52:06
    okay so the person who receives the
  • 00:52:07
    blood does not have antibodies to the
  • 00:52:09
    donors but basically guys a b can
  • 00:52:13
    receive can receive
  • 00:52:16
    blood from
  • 00:52:19
    anyone
  • 00:52:21
    or can receive blood
  • 00:52:26
    from o only this is very important
  • 00:52:29
    because look a b it is important that
  • 00:52:33
    the person who receives the blood
  • 00:52:34
    recipient does not have antibodies to
  • 00:52:37
    the donors but so A B has no antibodies
  • 00:52:39
    that's why he or she can receive from
  • 00:52:41
    anyone o has both antibodies that is why
  • 00:52:43
    he or she can only receive for more now
  • 00:52:45
    let's look at B
  • 00:52:46
    B has anti-a antibodies okay B has
  • 00:52:50
    anti-a antibodies so the person at B
  • 00:52:53
    cannot receive a antigen that is why
  • 00:52:57
    they cannot receive the a antigens which
  • 00:53:00
    is present in
  • 00:53:02
    A and A B so A and A B are of limits it
  • 00:53:06
    has to be D
  • 00:53:07
    b n over here B will obviously be clear
  • 00:53:09
    because a person with B group can
  • 00:53:11
    receive B from you know blood from B
  • 00:53:14
    group and O has no antigens right so
  • 00:53:16
    it's totally safe
  • 00:53:18
    okay
  • 00:53:21
    so since o has no antigens on the RBC uh
  • 00:53:25
    so the NTA antibodies won't react with
  • 00:53:27
    anyone there is a counter argument you
  • 00:53:29
    can set it up but o has anti-b
  • 00:53:32
    antibodies right which can react with
  • 00:53:34
    the B antigen on the B blood group but
  • 00:53:35
    thing is the antibodies in the uh from
  • 00:53:39
    the donor become very you know
  • 00:53:44
    dilute in the plasma of the recipient
  • 00:53:46
    okay that's the reason why you should
  • 00:53:48
    never look at the antibodies of the
  • 00:53:51
    donor you only need to look at the
  • 00:53:54
    antibodies of the recipient
  • 00:53:56
    okay and the antigens of the
  • 00:54:00
    donor
  • 00:54:03
    let's try and use a diagram to show four
  • 00:54:05
    types of cells involved in primary
  • 00:54:06
    immune response
  • 00:54:07
    cell type 1 release chemicals that
  • 00:54:09
    stimulate phagocytes to engulf antigens
  • 00:54:14
    cell type 2
  • 00:54:16
    distress sales infected viruses which
  • 00:54:18
    would be released into the body so that
  • 00:54:19
    tree produced antibodies required to
  • 00:54:21
    bind to antigen plasma cells produce
  • 00:54:23
    antibodies okay and plasma cells are
  • 00:54:25
    derived from
  • 00:54:27
    B lymphocytes so cell 3 is actually a b
  • 00:54:29
    lymphocyte
  • 00:54:31
    um cell type 4 recognize the four
  • 00:54:32
    antigen move towards it and surrounds it
  • 00:54:37
    so that's clearly macrophage so we know
  • 00:54:40
    about this
  • 00:54:41
    now what about cell one and two cell two
  • 00:54:43
    destroys the cells so clearly the name
  • 00:54:46
    Cicero it needs to be the T killer cell
  • 00:54:50
    sorry yeah articularly still tap to my
  • 00:54:53
    bed I just marked the wrong one so it
  • 00:54:54
    should be C so this is the T killer
  • 00:54:58
    cytotoxic T cell
  • 00:55:00
    one is the T helper cell it's secretes
  • 00:55:02
    chemical cytokines
  • 00:55:04
    this is the B lymphocyte which is
  • 00:55:08
    derived to form uh plasma this is the
  • 00:55:11
    macrophage it is involved in Elgin
  • 00:55:14
    engulfing the uh
  • 00:55:16
    a bacteria anyway guys so that is it
  • 00:55:20
    uh if you do like the videos remember to
  • 00:55:22
    subscribe to the channel I'm gonna link
  • 00:55:24
    the playlist for paper one up here the
  • 00:55:27
    video for May June 2022 paper one one up
  • 00:55:31
    here and the video for May June 2022
  • 00:55:34
    went one three down here when I solve it
  • 00:55:37
    and if I've made any mistakes in the
  • 00:55:39
    video please feel free to comment down
  • 00:55:40
    below see you guys
Tags
  • biology
  • AS Level
  • exam review
  • 9700
  • Cambridge
  • magnification
  • cell structures
  • enzymes
  • gas exchange
  • medical school