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Biology Revision Year 1 > Exam Questions > Flashcards

Exam Questions Flashcards

1
Q

What is a vaccination (2)

A

the injection of an inactive antigen to stimulate the formation of memory B cells

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2
Q

A mother who was infected with HIV gave birth to a baby. The baby tested positive for HIV using the ELISA test, explain why this does not prove that the baby has HIV

A

children receive HIV antibodies from their mothers, so there is always a colour change before 18 months

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3
Q

Scientists measured the conc of nicotine in the blood of 2 volunteers who smoked the same number of cigarettes each day. Suggest 2 reasons why the results was different (2)

A

different metabolic rates, amount of nicotine in cigarettes, amount inhaled, blood volume

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4
Q

give 2 structures a bacterial cell may have that a white blood cell would not

A

flagella

capsule

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5
Q

Explain how the effects of diarrhoea on the body can be treated (2)

A

Oral rehydration therapy

replace lost water and salts

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6
Q

Oral rehydration solutions (ORS) are used to treat diarrhoeal disease. What does an ORS consist of and how does it work?(5)

A

Contains glucose, starch, carbohydrates, and salt
this is taken up by the lumen and lowers the water potential
therefore water is taken up by osmosis

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7
Q

Explain the differences in structure between a bacterium and an epithelial cell (5)

A

bacteria is a prokaryote, has smaller ribosomes, no nucleus or membrane bound organelles , flagella, plasmid

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8
Q

Describe and explain the roles of diffusion, facilitated diffusion and active transport in the absorption of digested food. (8)

A

Diffusion - movement down concentration gradient eg) monoglycerides into epithelial cells
Facilitated diffusion - movement down concentration gradient using carrier/channel proteins
Active transport - movement against concentration gradient using ATP eg) co transport of Na and Glucose

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9
Q

Describe the process involved in the absorption of the products of starch digestion (7)

A

Glucose moves with sodium via channel protein
sodium removed via active transport into blood
maintaining low concentration of sodium/concentration gradient
glucose moves into blood via fac diff

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10
Q

Describe how sugars are absorbed from the small intestine into the blood of a mammal (6)

A

AT and Diff into capillaries
ATP used
glucose actively transported into epithelial cells via protein carriers
fac diff from epithelial ——> blood

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11
Q

Explain how the small intestine is adapted to its function in the absorption of the products of digestion

A 
thin - short diffusion distance
high SA 
villi/ microvilli
lots of mitochondria for AT 
carrier proteins present in membranes
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12
Q

Cells contain suppressor genes which code for proteins controlling cell division and growth. Describe what is meant by a mutation, and explain how a mutation in these genes may lead to the development of a malignant tumour (6)

A
  • mutation is change to the DNA base sequence
  • This results in the suppressor gene having the wrong code
  • different AA sequence coded for
  • non functional protein
  • Uncontrolled mitosis
  • metastasis via lymph/blood
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13
Q

Explain how a mutation in a gene can result in a strain lacking a particular enzyme (4)

A
  • incorrect bases sequence
  • incorrect mRNA codons —–> incorrect tRNA anticodons
  • changes the tertiary structure
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14
Q

Suggest why mutant genes can be identified more easily in Haploid fungi than in Diploid fungi (4)

A
  • diploid have 2 sets of chromosomes
  • in haploid all alleles are expressed
  • diploid may not express recessive alleles unless homozygous
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15
Q

Describe the role of a ribosome in the production of a polypeptide. Do NOT include transcription in your answer (3)

A
  1. mRNA binds to ribosome;
  2. binding sites between codon and anticodon
  3. tRNA with anticodons to binds
  4. (Catalyses) formation of peptide bond between amino acids (held by tRNA molecules);
  5. Moves along (mRNA to the next codon)/translocation described;
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16
Q

Describe the structure of glycogen. (2)

A

highly branched polymer of alpha glucose

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17
Q

Suggest how glycogen acts as a source of energy. (2)

A

glycogen can be hydrolysed to form glucose for respiration

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18
Q

Suggest and Explain 2 ways the cell surface membrane of the cells lining the uterus may be adapted to allow rapid transportation of nutrients (2)

A

1) Membrane may be folded to increase SA for rapid diffusion
2) The membrane may have a lot of channel proteins for fac diff

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19
Q

Sodium ions are absorbed by cells lining the gut. Some of these membranes have carrier proteins called NHE3. NHE3 actively transports one sodium ion in in exchange for one proton out.
Use knowledge of transport across cell membranes to suggest how NHE3 does this (3)

A

using ATP
the sodium and proton bind to the proton
Protein alters shape
co transport

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20
Q

Describe how bacteria divide (2)

A

Binary fission
replication of circular DNA
Division of cytoplasm 2 x daughter
each single DNA copy

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21
Q

Some proteases are secreted as extracellular enzymes by bacteria.
Suggest one advantage to a bacterium of secreting an extracellular protease in its environment + explain. (2)

A

proteases hydrolyse proteins

ability to absorb amino acids for growth and repair

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22
Q

Give 3 environmental variables that should be controlled when growing the plants before treatments with different sprays

A

temperature, CO2 conc, mineral ion conc,light intensity, humidity

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23
Q

Suggest one reason why the scientists ensured the temp the same, and why the leaf discs were shaken. (2)

A

temp - didn’t want to affect the kinetic energy

shaken - to maintain conc grad

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24
Q

Describe how phagocytosis of a virus leads to presentation of its antigens

A

the phagocyte engulfs the pathogen into a phagocytic vacuole
the lysosomes attach and release lysosymes/ hydrolytic enzymes
the phagocyte then becomes antigen presenting

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25
Q

Describe how the presentation of a virus antigen leads to the secretion of an antibody against this virus antigen (3)

A

the helper t cell is activated by the antigens on the cell surface membrane
stimulating the production of B cells
clone into plasma cells which secrete antibodies

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26
Q

Collagen is a protein produced by cells in joints eg) the knee
RA is an autoimmune disease. In an autoimmune disease, a persons immune system attacks their own cells. RA causes pain and swelling to the joints
Scientists found a virus that produces a protein very similar to human collagen
Suggest how the immune response to this viral protein can result in the development of RA. (2)

A

the antibody against the virus will bind to the collagen

the human collagen is destroyed

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27
Q

Complete the taxon (hierarchical order) (1)

A

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

28
Q

State 3 comparisons of genetic diversity that scientists use (3)

A

mRNA sequence, DNA sequence (hybridisation), amino acid sequence

29
Q

Explain 3 ways in which an insects TRACHEAL system is adapted for efficient gas exchange (3)

A

highly branched so short diffusion distance, tracheoles have thin walls so short diffusion distance, fluid moves out during exercise (anaerobic respiration) forcing air in/ faster diffusion

30
Q

The damesfly larva is a carnivore that actively hunts prey. It has gills to obtain oxygen from water. Explain how the presence of gills adapts the damesfly to it’s way of life (2)

A

higher metabolic rate

more oxygen used

31
Q

Contrast how an optical microscope and a TEM work and contrast the limitations of their use when studying cells (6)

A

optical uses light waves TEM uses electrons
TEM has a higher resolution
TEM can distinguish individual organelles
TEM B+W Optical colour
TEM specimen has to be dead
TEM focusses using magnets whereas optical uses lenses

32
Q

A technician investigated the affect of temperature on the rate of an enzyme controlled reaction. At each temperature, he started the reaction using the same concentration of substrate. Give 2 other factors he would have controlled (2)

A

concentration of enzyme, pH, volume of substrate

33
Q

Explain the difference in the rates of reaction at 60 degrees c and 37 degrees c between 40 and 60 minutes (4)

A

at 60 the enzymes have denatured, so the active sites have changed shape and the reaction stops sooner.
There are different conc because despite substrate still being available it is not converted to product at 60 degrees c

34
Q

Describe how O2 in the air reaches capillaries surrounding alveoli in the lungs (4)

A

trachea, bronchi/ bronchioles
air forced in down the pressure gradient
diffusion down the conc grad into the capillaries
across alveolar epithelium
across capillary epithelium

35
Q

The traps in the canopy were set at 16 to 27 m above ground level, suggest why there was such variation in the height of the traps (1)

A

trees vary in height

36
Q

Explain how cellulose molecules are adapted for their function in plant cells (3)

A

structural in the cell wall
long straight chains
intermolecular hydrogen bonds increase strength

37
Q

Contrast the processes of Facilitated diffusion and active transport (3)
Contrast = both justified

A

Active transport uses ATP WHEREAS Facilitated diffusion is passive
Facilitated diffusion uses carrier/channel proteins WHEREAS AT uses only carrier
AT goes against the conc grad WHEREAS fac diff goes down the conc grad

38
Q

In this investigation, what is meant by genetic diversity? (1)

A

The number of different alleles of each gene

39
Q

Emphysema is a disease that affects the lungs. It causes a decrease in the number of alveoli. It may also cause the alveolar walls to become thickened.

Explain why people with emphysema may need to use oxygen masks (3)

A

SA is decreased
Thickened wall increases diffusion pathway
Mask increases concentration gradient

40
Q

Explain how the ventilation system of a fish and the structure of its gills result in efficient uptake of oxygen from water (6)

A

Lamellar/ filaments
Secondary lamellae increase surface area
Large no of capillaries remove O2
Thin epithelium means short diffusion pathway
Pressure changes bring in more water / maintain conc grad
Countercurrent flow prevent equilibrium/ conc grad maintained

41
Q

The ELISA test only detects the presence of HIV antibodies. Give 2 reasons it cannot be used to determine if a person has aids/ (2)

A

look for symptoms of aids

aids affects the number of t helper cells

42
Q

A control well is set up every time the test is used, this is treated the same accept blood plasma is replaced with salt solution. Suggest the two purposes of the control well. (2)

A

ensure only the enzyme is causing the colour change

to ensure the washing is affective

43
Q

During replication the two DNA strands separate and each acts as a template for the production of a new strand. As new DNA strands are produced, nucleotides can only be added in the 5’ to 3’ direction. Explain why (4)

A

the enzyme DNA polymerase
is specific to that orientation
will only bind with the 5’ end of template
and only the phosphate end of the developing strand

44
Q

Describe the Mass Flow hypothesis for the mechanism of translocation (4)

A

At the source assimilates are loaded into the phloem by active transport by companion cells
this decreases the water potential causing water to move into the sieve tube by osmosis
This increases the pressure causing mass movement to the sink
Sugars are used up in respiration or converted into starch for storage

45
Q

Describe how mRNA is produced in the nucleus of a cell (6)

A

DNA helicase separates the DNA strands by breaking the hydrogen bonds between bases
free RNA nucleotides form complementary base pairing with one strand
RNA nucleotides are joined together by RNA polymerase
pre- mRNA is spliced to remove introns

46
Q

Describe the structure of proteins (5)

A

Proteins are a polymer of amino acids joined together by peptide bonds
formed by condensation reactions
Primary structure is amino acid chain order
secondary structure alpha helix/ beta pleated sheets (H+ bonds
Tertiary structure is 3D folding (H+ bonds, disulphide bridges, ionic)
Quaternary - multiple amino acid chains

47
Q

Describe how proteins are digested in the human gut (4)

A

hydrolysis of peptide bonds
Endopeptidases hydrolyse polypeptides into smaller chains
Exopeptidases remove terminal amino acids
Dipeptidases hydrolyse dipeptides into amino acids

48
Q

Describe and explain 3 pieces of evidence that would imply a cell is undergoing mitosis (3)

A

DNA has replicated so there are 2 x chromatids joined together
We can see the chromosomes as they have condensed
The chromosomes are not arranged in homologous pairs

49
Q

When preparing the cells for observation the scientists placed them into a solution that had a higher water potential than the cytoplasm.
Suggest how this procedure moved the chromosomes apart (2)

A

water moved into the cell by osmosis

the cell cytoplasm gets bigger

50
Q

Give 2 ways the arrangement of prokaryote DNA is different to the arrangement of human DNA (2)

A

Human DNA is associated with histones Prokaryote DNA isn’t.
circular vs linear
single stranded vs double stranded
present as plasmids

51
Q

A student is investigating the affect of surface area on osmosis in cubes of potatoes. Describe the method the students would have used to obtain the results in Figure 3, start after the cubes have been cut. (3)

A
  • ensure all cut surfaces are exposed to the sucrose solution - shake it
  • control temperature - use water bath and thermometer
  • dry off using paper towel
  • measure mass using zeroed balance
52
Q

Scientists were investigating bee population, suggest how the scientists could ensure they correctly identified each sample. (1)

A
  • allow close examination

- use key to identify species

53
Q

Suggest and explain two ways in which the scientists could have improved the methods used for data collection. (bee population) (2)

A
  • collect at more times of the year
  • calculate IOD
  • collect at more sites
54
Q

Explain how the formation of an ESC increases the rate of reaction (2)

A

Enzymes lower the activation energy due to bonds breaking

55
Q

The scientists critical value at P = 0.05 is 3.841
what does this result suggest about the difference between the observed and expected, and what can the scientists therefore conclude? (2)

A
  • There is a less than 0.05/ 5% probability that the difference between observed and expected are due to chance
  • they can therefore reject the null hypothesis
56
Q

When a person is bitten by a snake anti venom is used as a treatment, it contains antibodies against the snake venom. This is an example of passive immunity.
Explain how the antivenom works and why it is used (2)

A
  • antigens in the snake venom bind to the toxin and cause it’s destruction
  • active immunity would be too slow/ passive immunity is faster
57
Q

In the procedure to produce antivenom a mixture of venoms from several snakes of the same species is used. Suggest why (2)

A
  • different form of antigen/ toxin
  • different mutations/ alleles
  • several antibodies complementary to the different antigens
58
Q

During vaccination, each animal is injected with a small volume of the venom. Two weeks later it is injected with a larger volume of venom
Use knowledge of the humoral immune system to explain this vaccination programme (3)

A

B cells specific to the venom reproduce by mitosis
clone into plasma cells with the specific antibody to the venom
stored in memory cells so quickly produce a lot of the antibody following the second exposure

59
Q

Describe the role of two named enzymes in the process of semi conservative replication of DNA (3)

A

DNA helicase breaks the H+ bonds between the bases to allow the complementary base pairing of free nucleotides
DNA polymerase catalyses the formation of phosphodiester bonds in the new DNA strand between nucleotides

60
Q

Compare and contrast the structure and properties of triglycerides and phospholipids (5)

A
  1. Both contain ester bonds (between glycerol and fatty acid);
  2. Both contain glycerol;
  3. Fatty acids on both may be saturated or unsaturated;
  4. Both are insoluble in water;
  5. Both contain C, H and O but phospholipids also contain P;
  6. Triglyceride has three fatty acids and phospholipid has two fatty acids plus phosphate group;
  7. Triglycerides are hydrophobic/non-polar and phospholipids have hydrophilic and hydrophobic region;
  8. Phospholipids form monolayer (on surface)/micelle/bilayer (in water) but triglycerides don’
61
Q

Describe how lactose is formed and where in the cell it would be attached to a polypeptide to form a glycoprotein (4)

A

lactose is made by the condensation reaction between glucose and galactose
forms a glycosidic bond
The lactose would be added to the polypeptide in the Golgi apparatus

62
Q

Suggest and explain two ways the cell-surface membranes of the cells lining the
uterus may be adapted to allow rapid transport of nutrients. (2)

A

folded membrane increases SA

protein channels/carriers for co transport, active transport, fac diff

63
Q

Sodium ions from salt (sodium chloride) are absorbed by cells lining the gut. Some
of these cells have membranes with a carrier protein called NHE3.
NHE3 actively transports one sodium ion into the cell in exchange for one proton
(hydrogen ion) out of the cell.
Use your knowledge of transport across cell membranes to suggest how NHE3
does this.
(3)

A

co transport using ATP

bind to receptor and alter shape

64
Q

High absorption of salt from the diet can result in a higher than normal
concentration of salt in the blood plasma entering capillaries. This can lead to a
build-up of tissue fluid.
Explain how. (2)

A
  1. (Higher salt) results in lower water potential of
    tissue fluid;
  2. (So) less water returns to capillary by osmosis
    (at venule end);
    OR
  3. (Higher salt) results in higher blood
    pressure/volume;
  4. (So) more fluid pushed/forced out (at arteriole
    end) of capillary;
65
Q

Some proteases are secreted as extracellular enzymes by bacteria.
Suggest one advantage to a bacterium of secreting an extracellular protease in its
natural environment.
Explain your answer.

A
  1. To digest protein;
  2. (So) they can absorb amino acids for
    growth/reproduction/protein synthesis/synthesis
    of named cell component;
    OR
    (So) they can destroy a toxic substance/protein;
66
Q

Give three environmental variables that should be controlled when growing the
plants before treatment with the different sprays. (2)

A 
1. Concentration of mineral ion/named mineral
ion in soil;
2. Soil pH;
3. Temperature;
4. Light intensity/wavelength/duration;
5. Distance between seeds/plants;
6. Volume of water given;
7. CO2 concentration;
8. Humidity;
67
Q

The adult damselfly uses a tracheal system for gas exchange.
Explain three ways in which an insect’s tracheal system is adapted for efficient gas
exchange.
[3 marks]

A
  1. Tracheoles have thin walls so short
    diffusion distance to cells;
  2. Highly branched/large number of
    tracheoles so short diffusion distance to
    cells;
  3. Highly branched/large number of
    tracheoles so large surface area (for gas
    exchange);
  4. Tracheae provide tubes full of air so fast
    diffusion (into insect tissues);
  5. Fluid in the end of the tracheoles that
    moves out (into tissues) during exercise
    so faster diffusion through the air to the
    gas exchange surface;
    OR
    Fluid in the end of the tracheoles that
    moves out (into tissues) during exercise
    so larger surface area (for gas exchange);
  6. Body can be moved (by muscles) to move
    air so maintains diffusion/concentration
    gradient for oxygen/carbon dioxide;

Biology Revision Year 1 (13 decks)

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