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AP® Biology flashcards Biology 101 flashcards
1
Q

Describe how a non-competitive inhibitor can reduce the rate of an
enzyme-controlled reactio

A
  1. Attaches to the enzyme at a site other than the
    active site;
  2. Changes (shape of) the active site

(So active site and substrate) no longer
complementary so less/no substrate can fit/bind;

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2
Q

The scientist concluded that pectin is a non-competitive inhibitor of the lipase enzyme.
Use Figure 1 to explain why the scientist concluded that pectin is a non-competitive
inhibitor.

A

(With inhibitor) increase substrate/lipid
(concentration) does not increase/affect/change
rate of reaction

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3
Q

No large lipid droplets are visible with the optical microscope in the samples from
suspension A.
Explain why.

A
  1. Emulsification;
  2. (Cannot be seen) due to resolution (of optical
    microscope);
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3
Q

The scientists estimated the mean mass of fibre eaten per day using a food frequency
questionnaire (FFQ).
The FFQ asks each person how often they have eaten many types of food over the
past year.
An alternative method to calculate fibre eaten is for a nurse to ask each person
detailed questions about what they have eaten in the last 24 hours.
Suggest one advantage of using the FFQ method and one disadvantage of using the
FFQ method compared with the alternative method.

A
  1. Over longer period so more representative
  2. Relies on (long term) memory so may not be
    accurate
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4
Q

What data would the students need to collect to calculate their index of diversity in
each habitat?

A

(Number of species and) number of individuals in
each species (in each habitat)

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5
Q

Give two ways the students would have ensured their index of diversity was
representative of each habitat.

A
  1. Random samples;
  2. Large number (of samples)
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6
Q

Modern farming techniques have led to larger fields and the removal of hedges
between fields

suggest why biodiversity decreases when farmers use larger fields

A

Less hedge Fewer species;

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7
Q

Farmers are now being encouraged to replant hedges on their land.
Suggest and explain one advantage and one disadvantage to a farmer of replanting
hedges on her farmland.

A
  1. Greater (bio)diversity so increase in predators of
    pests
  2. Reduced land area for crop growth/income
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8
Q

The scientists calculated a P value of 0.03 when testing their null hypothesis.
What can you conclude from this result? Explain your answer

A
  1. Probability that difference (in frequency of
    births above 4500 g) is due to chance is
    less than 0.05
  2. Reject null hypothesis;
  3. Presence of KIR2DS1/allele does
    (significantly) affect the frequency of high
    birth mass;
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9
Q

Describe the structure of the human immunodeficiency virus (HIV).
[

A
  1. RNA (as genetic material);
  2. Reverse transcriptase;
  3. (Protein) capsomeres/capsid;
  4. (Phospho)lipid (viral) envelope
  5. Attachment proteins;
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10
Q

your knowledge of the immune response to suggest why
HIV controllers do not develop symptoms of AIDS.

A
  1. (All) have more T helper/CD4 cells;
  2. Lower viral load to infect/destroy helper T/CD4
    cells;
  3. (So more/continued) activation of B
    cells/cytotoxic T cells/phagocytes;
  4. (With B cells more/continued) production of
    plasma cells/antibodies
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11
Q

The scientists determined the percentage of heart cells undergoing DNA replication
by using a chemical called BrdU. Cells use BrdU instead of nucleotides containing
thymine during DNA replication.
0 6 . 2 Describe how BrdU would be incorporated into new DNA during semi-conservative
replication.

A
  1. DNA helicase;
  2. Breaks hydrogen bonds (between 2 DNA
    strands);
  3. BrdU complementary to adenine (on template
    strand)
  4. DNA polymerase joins (adjacent) nucleotides (to
    incorporate BrdU into the new DNA strand);
  5. Phosphodiester bonds form (between
    nucleotides);
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12
Q

Cells with BrdU in their DNA are detected using an anti-BrdU antibody with an enzyme
attached.
Use your knowledge of the ELISA test to suggest and explain how the scientists
identified the cells that have BrdU in their DNA

A
  1. Add antibody (anti-BrdU with enzyme attached)
    to cells/DNA
  2. Wash (cells/DNA) to remove excess/unattached
    antibody
  3. Add substrate to cause colour change
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13
Q

Suggest how Ulva lactuca is able to survive without xylem tissue.

A

Short diffusion pathway (to cells)

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14
Q

Ulva prolifera also produces haploid, mobile single cells that can fuse to form a zygote.
Suggest and explain one reason why successful reproduction between Ulva prolifera
and Ulva lactuca does not happen.

A
  1. They are different species;
  2. (So) if fused together they would not
    produce fertile offspring
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15
Q

Use your knowledge of gas exchange in leaves to explain why plants grown in soil
with very little water grow only slowly

A
  1. Stomata close;
  2. Less carbon dioxide (uptake) for less
    photosynthesis/glucose production;
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16
Q

Mammals such as a mouse and a horse are able to maintain a constant body
temperature.
Use your knowledge of surface area to volume ratio to explain the higher metabolic
rate of a mouse compared to a horse.

A
  1. (Smaller so) larger surface area to volume
    ratio;
  2. More/faster heat loss (per gram/in relation
    to body size);
  3. (Faster rate of) respiration/metabolism
    releases heat;
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17
Q

Explain five properties that make water important for organisms

A
  1. A metabolite in condensation/hydrolysis/
    photosynthesis/respiration;
  2. A solvent so (metabolic) reactions can occur
  3. High heat capacity so buffers changes in
    temperature;
  4. Large latent heat of vaporisation so provides a
    cooling effect (through evaporation);
  5. Cohesion (between water molecules) so
    supports columns of water (in plants);
  6. Cohesion (between water molecules) so
    produces surface tension supporting (small)
    organisms;
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18
Q

Describe the biochemical tests you would use to confirm the presence of lipid,
non-reducing sugar and amylase in a sample.

A

Lipid
1. Add ethanol/alcohol then add water and
shake/mix
OR
Add ethanol/alcohol and shake/mix then
pour into/add water;
2. White/milky emulsion

Non-reducing sugar
3. Do Benedict’s test and stays blue/negative;
4. Boil with acid then neutralise with alkali;
5. Heat with Benedict’s and becomes
red/orange (precipitate);

Amylase
6. Add biuret (reagent) and becomes
purple/violet/mauve/lilac;
7. Add starch, (leave for a time), test for
reducing sugar/absence of starch;

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19
Q

Describe the chemical reactions involved in the conversion of polymers to monomers
and monomers to polymers.
Give two named examples of polymers and their associated monomers to illustrate
your answer.

A
  1. A condensation reaction joins monomers
    together and forms a (chemical) bond and
    releases water;
  2. A hydrolysis reaction breaks a (chemical)
    bond between monomers and uses water;
  3. A suitable example of polymers and the
    monomers from which they are made;
  4. A second suitable example of polymers and
    the monomers from which they are made;
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20
Q

The movement of Na+ out of the cell allows the absorption of glucose into the
cell lining the ileum.
Explain how.

A
  1. (Maintains/generates) a
    concentration/diffusion gradient for Na+
    (from
    ileum into cell);
  2. Na+ moving (in) by facilitated diffusion,
    brings glucose with it
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20
Q

Explain the function of this ATP hydrolase.

A
  1. (ATP to ADP + Pi ) Releases energy;
  2. (energy) allows ions to be moved against a
    concentration gradient
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21
Q

Describe and explain two features you would expect to find in a cell specialised for
absorption.

A
  1. Folded membrane/microvilli so large surface
    area (for absorption);
  2. Large number of
    co-transport/carrier/channel proteins so fast
    rate
  3. Large number of mitochondria so make
    (more) ATP (by respiration)
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22
Q

Describe how amino acids join to form a polypeptide so there is always NH2 at
one end and COOH at the other end.

A
  1. One amine/NH2 group joins to a
    carboxyl/COOH group to form a peptide
    bond;
  2. (So in chain) there is a free amine/NH2 group
    at one end and a free carboxyl/COOH group
    at the other
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23
Q

Describe the role of micelles in the absorption of fats into the cells lining the ileum

A

Micelles include bile salts and fatty acids;
2. Make the fatty acids (more) soluble in water;
3. Bring/release/carry fatty acids to cell/lining (of the
ileum);
4. Maintain high(er) concentration of fatty acids to
cell/lining (of the ileum);
5. Fatty acids (absorbed) by diffusion;

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24
Q

At Q on Figure 3 there is a small increase in pressure and in rate of blood flow in the
aorta.
Explain how this happens and its importance.

A
  1. Elastic recoil (of the aorta wall/tissue);
  2. Smooths the blood flow
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25
Q

Describe the role of DNA polymerase in the semi-conservative replication of DNA

A
  1. Joins (adjacent DNA) nucleotides;
  2. (Catalyses) condensation (reactions);
  3. (Catalyses formation of) phosphodiester bonds
    (between adjacent nucleotides);
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26
Q

Cyclin D stimulates the phosphorylation of DNA polymerase, which activates the
DNA polymerase.
Describe how an enzyme can be phosphorylated

A
  1. Attachment/association of (inorganic) phosphate
    (to the enzyme);
  2. (Released from) hydrolysis of ATP
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27
Q

Explain why death of alveolar epithelium cells reduces gas exchange in human lungs

A
  1. Reduced surface area;
  2. Increased distance for diffusion;
  3. Reduced rate of gas exchange;
28
Q

Some tumour cells contain higher than normal concentrations of cyclin D.
Use Figure 5 to suggest why higher than normal concentrations of cyclin D could
result in a tumour.

A
  1. Shortens interphase
  2. Fast(er) cell cycle/division/multiplication/mitosis
  3. (Resulting in) a mass/group of
    abnormal/excessive cells;
29
Q

Alpha-gal is a disaccharide found in red meat.
Alpha-gal is made of two galactose molecules. Galactose has the chemical formula
C6H12O6
Give the chemical formula for the disaccharide, alpha-gal, and describe how it is
formed from two galactose molecules.

A
  1. C12H22O11;
  2. Condensation reaction
30
Q

Suggest how one antibody can be specific to tick protein and to alpha-gal.

A
  1. (Part of tick protein and alpha-gal) have a similar
    shape/structure;
  2. Antibody is complementary to both (tick protein
    and alpha-gal)
31
Q

Complete Table 2 to show three differences between DNA in the nucleus of a
plant cell and DNA in a prokaryotic cell.

A
  1. (Associated with) histones/proteins v no
    histones/proteins;
  2. Linear v circular;
  3. No plasmids v plasmids;
  4. Introns v no introns;
  5. Long(er) v short(er)
32
Q

Define ‘non-coding base sequences’ and describe where the non-coding multiple
repeats are positioned in the genome.

A
  1. DNA that does not code for protein/polypeptides
  2. (Positioned) between genes;
33
Q

Describe how mRNA is formed by transcription in eukaryotes.

A
  1. Hydrogen bonds (between DNA bases) break;
  2. (Only) one DNA strand acts as a template;
  3. (Free) RNA nucleotides align by complementary
    base pairing;
  4. (In RNA) Uracil base pairs with adenine (on
    DNA)
  5. RNA polymerase joins (adjacent RNA)
    nucleotides;
  6. (By) phosphodiester bonds (between adjacent
    nucleotides);
  7. Pre-mRNA is spliced (to form mRNA)
34
Q

Describe how a polypeptide is formed by translation of mRNA.

A
  1. (mRNA attaches) to ribosomes
  2. (tRNA) anticodons (bind to) complementary
    (mRNA) codons;
  3. tRNA brings a specific amino acid;
  4. Amino acids join by peptide bonds;
  5. (Amino acids join together) with the use of ATP;
  6. tRNA released (after amino acid joined to
    polypeptide);
  7. The ribosome moves along the mRNA to form
    the polypeptide;
35
Q

Define ‘gene mutation’ and explain how a gene mutation can have:
* no effect on an individual
* a positive effect on an individual.

A

(Definition of gene mutation)
1. Change in the base/nucleotide (sequence of
chromosomes/DNA);
2. Results in the formation of new allele;
(Has no effect because)
3. Genetic code is degenerate (so amino acid
sequence may not change);
OR
Mutation is in an intron (so amino acid sequence
may not change);
4. Does change amino acid but no effect on tertiary
structure;
5. (New allele) is recessive so does not influence
phenotype;
(Has positive effect because)
6. Results in change in polypeptide that positively
changes the properties (of the protein)
OR
Results in change in polypeptide that positively
changes a named protein;
7. May result in increased reproductive success

36
Q

Describe the induced-fit model of enzyme action and how an enzyme acts as a
catalyst.

A
  1. Substrate binds to the active site/enzyme
  2. Active site changes shape (slightly) so it is
    complementary to substrate
  3. Reduces activation energy;
37
Q

Suggest and explain a procedure the scientists could have used to stop each reaction

A
  1. Boil
    OR
    Add (strong) acid/alkali;
  2. Denatures the enzyme/ATP synthase;
38
Q

Explain the change in ATP concentration with increasing inorganic phosphate
concentration.

A
  1. (With) increasing Pi concentration, more
    enzyme-substrate complexes are formed;
39
Q

Explain the advantage for larger animals of having a specialised system that
facilitates oxygen uptake

A
  1. Large(r) organisms have a small(er) surface
    area:volume (ratio);
  2. Overcomes long diffusion pathway
40
Q

Explain how the counter-current principle allows efficient oxygen uptake in the
fish gas exchange system

A
  1. Water has low(er) oxygen partial
    pressure/concentration (than air);
  2. So (system on outside) gives large surface area
    (in contact with water)
41
Q

Describe how one amino acid is added to a polypeptide that is being formed at a
ribosome during translation

A
  1. tRNA brings specific amino acid (to ribosome);
  2. Anticodon (on tRNA) binds to codon (on
    mRNA);
  3. Amino acids join by condensation reaction
    (using ATP)
42
Q

Suggest two ways the student could improve the quality of his scientific drawing of the
blood vessels in this dissection.

A
  1. Only use single lines/do not use sketching
    (lines)/ensure lines are continuous/connected;
  2. Add labels/annotations/title;
  3. Add magnification/scale (bar);
  4. Draw all parts to same scale/relative size;
  5. Do not use shading/hatching;
43
Q

Describe two precautions the student should take when clearing away after the
dissection.

A

Carry/wash sharp instruments by holding handle
2. Disinfect instruments/surfaces;
3. Disinfect hands

44
Q

Use your knowledge of phagocytosis to describe how an ADC enters and kills the
tumour cell.

A
  1. Cell ingests/engulfs the antibody/ADC
  2. Lysosomes fuse with vesicle/phagosome
    (containing ADC);
  3. Lysozymes breakdown/digest the antibody/ADC
    to release the drug
45
Q

Suggest and explain two further investigations that should be done before this ADC
is tested on human breast cancer patients

A
  1. Tested on other mammals to check for
    safety/side effects;
  2. Tested on (healthy) humans to check for
    safety/side effects;
  3. See if repeat doses stop the tumours regrowing
    (in Group J);
  4. Investigate different concentrations of ADC to
    find suitable/safe dosage;
46
Q

Describe how a triglyceride molecule is formed

A
  1. One glycerol and three fatty acids;
  2. Condensation (reactions) and removal of
    three molecules of water;
  3. Ester bond(s) (formed);
47
Q

Describe the structure of DNA.

A
  1. Polymer of nucleotides;
  2. Each nucleotide formed from deoxyribose, a
    phosphate (group) and an organic/nitrogenous base;
  3. Phosphodiester bonds (between nucleotides);
  4. Double helix/2 strands held by hydrogen bonds;
  5. (Hydrogen bonds/pairing) between adenine, thymine
    and cytosine, guanine;
48
Q

Name and describe five ways substances can move across the cell-surface
membrane into a cell.

A
  1. (Simple) diffusion of small/non-polar molecules down a
    concentration gradient;
  2. Facilitated diffusion down a concentration gradient via
    protein carrier/channel;
  3. Osmosis of water down a water potential gradient;
  4. Active transport against a concentration gradient via
    protein carrier using ATP;
  5. Co-transport of 2 different substances using a carrier
    protein
49
Q

0 1 . 1 Describe the structure and function of the nucleus.

A
  1. Nuclear envelope and pores
    DNA with histones;
    (Holds/stores) genetic information/material
    for polypeptides (production)
    Production of mRNA/tRNA
50
Q

Name the main polymer that forms the following cell walls.

Plant cell wall
Fungal cell wal

A

Cellulose (plants) and
Chitin (fungi);

51
Q

Suggest one reason the scientists used biomass instead of the number of individuals
of each plant species when collecting data to measure diversity.

A

Individual organisms could not be
identified/separated

52
Q

Give the three structural features found in all virus particles and describe the function
of one of these features.

A
  1. Genetic material, capsid and attachment protein;
  2. Genetic material codes for (viral) protein
    Attachment protein bind to receptors
53
Q

Explain why viruses are described as acellular and non-living.

A
  1. (Acellular) no cell(-surface) membrane
  2. (Non-living) have no metabolism/metabolic
    reactions
54
Q

Give one reason why antibiotics are not effective against viruses

A

Do not have bacterial structures/enzymes

55
Q

Chitin keeps the tracheae open in the tracheal system of gas exchange in an insect.
Gas exchange does not occur in the tracheae.
Explain the importance of one adaptation of the gas exchange surface in the tracheal
system of an insect.

A
  1. Tracheole (wall) thin/one cell thick;
  2. (So) rapid diffusion (into cells
56
Q

Lignin is a polymer found in the walls of xylem vessels in plants. Lignin keeps the
xylem vessel open as a continuous tube.
Explain the importance of the xylem being kept open as a continuous tube

A
  1. (Allows unbroken) water column
    . Cohesion from H bonds between (all) water
    (molecules)
57
Q

Describe two functions of the Golgi apparatus in a eukaryotic cell.

A
  1. Modify/package/transport proteins
  2. Modify/package/transport lipids
  3. Forms/releases vesicles/lysosomes;
58
Q

In Africa today, most of the human population are resistant to malaria caused by
P. vivax.
Use your knowledge of natural selection to explain why this resistance is so common
in Africa

A
  1. Mutation produced allele;
  2. Those with allele/resistance less likely to/do not
    get malaria/P vivax
  3. (So more likely to) reproduce and pass on the
    allele;
  4. (Over generations) allele frequency
    increases;
59
Q

Some hospital patients suffer from diarrhoea caused by infection with the bacterium
Clostridium difficile. The C. difficile bacteria release toxins. These toxins cause the
diarrhoea.
The toxins damage the cells lining the ileum, causing them to lose their microvilli.
The damage to the cells reduces the absorption of the products of digestion and
reduces the absorption of water, resulting in diarrhoea.
Explain why the damage to the cells lining the ileum reduces absorption of the
products of digestion and why this reduces absorption of water.

A
  1. Reduced surface area
  2. Decreases water potential in ileum/lumen
  3. (So) water moves out of cells/into ileum
    by osmosis
60
Q

To be used as passive immunity treatment, the anti-toxin antibody would be injected.
If it was given by mouth, it would be digested.
Describe how the anti-toxin antibody would be digested.

A
  1. Peptide bonds hydrolysed;
  2. Endopeptidase(s) break internal (peptide) bonds;
  3. Exopeptidase(s) break terminal (peptide) bonds;
  4. (Membrane-bound) dipeptidase(s) break
    dipeptides to amino acids;
61
Q

The student added 100 mm3 of each bacterial culture from its glass bottle onto a
separate agar plate. She spread each bacterial culture evenly over the agar using a
spreader.
Describe the aseptic techniques she should use

A
  1. Wash hands with soap
  2. Use sterile pipette/syringe (to transfer bacteria);
  3. (Remove bottle lid and) flame neck of bottle;
  4. Lift lid of (agar) plate at an angle;
  5. Work close to upward air movement;
  6. Use sterile spreader;
  7. Place pipette/spreader into disinfectant
    (immediately after use);
62
Q

Define genome and proteome.

A
  1. Complete set of genes in a cell
  2. (Full) range of proteins that a cell can produce
63
Q

MiTMAB acts as a non-competitive inhibitor of an enzyme called dynamin.
Suggest how MiTMAB can cause dynamin to become inactive.

A
  1. (MiTMAB) binds (to dynamin) other than the
    active site;
  2. Changes the shape of (dynamin) active site
  3. Not complementary so substrate does not bind
    (to active site)
64
Q

Suggest why the fused cells allow continuous production of monoclonal antibodies

A
  1. (Cancer/fused cells) divide/replicate
    rapidly/uncontrollably;
  2. B cells produce (monoclonal) antibody;
65
Q

The dengue virus causes damage to capillaries so that blood proteins move out of the
capillaries into the tissue fluid.
Explain how this would affect the return of tissue fluid into the capillaries.
[

A
  1. Increases water potential of blood/capillary
  2. (So) less water returns to blood/capillaries (by
    osmosis)
66
Q

Describe how a quaternary protein is formed from its monomers.
Do not include the process of translation in your answer.

A
  1. Amino acids joined by peptide bond(s);
  2. (By) condensation reaction(s);
  3. Secondary structure is formed by hydrogen
    bonding;
  4. Tertiary structure formed by interactions
    (between R groups);
  5. Quaternary structure contains >1 polypeptide
67
Q

Describe the structure of DNA and the structure of a chromosome.

A
  1. Polymer of nucleotides;
  2. (Nucleotide) consists of deoxyribose,
    phosphate and an organic/nitrogenous base;
  3. Phosphodiester bonds (between nucleotides);
  4. DNA double helix held by H bonds
  5. (Hydrogen bonds/pairing) between adenine,
    thymine and cytosine, guanine;
  6. DNA is associated with histones/proteins;
  7. (During mitosis/when visible) chromosome
    consists of tw
68
Q

Mutation can result in an increase in genetic variation within a species.
Describe and explain the other processes that result in increases in genetic variation
within a species.

A
  1. Independent segregation of homologous
    Chromosomes/pairs;
  2. Crossing over between homologous
    chromosomes/pairs;
  3. Random fertilisation of gametes;
  4. (Produces) new combinations of alleles;

Biology (58 decks)

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