Wrong Qs- L6th EOY

Question 1

Describe an explains one other process (not a mutation) which may result in an increase in genetic diversity (4 marks):

Answer 1

• species may interbreed with one another to produce offspring which may result in variation
• independent segregation of homologous chromosomes
• crossing over of chromatids
• random fertilisation of gametes- produces a new combination of gametes

Question 2

Descibr an explain the processes that occur during meiosis that increase genetic variation (5 marks):

Answer 2

1. Homologous chromosomes pair up
2. Independent segregation of chromosomes
3. Maternal + paternal chromosomes are shuffled into any combination
4. Crossing over leads to exchange of parts of non-sister chromatids between homologous chromosomes
5. Both create new combinations of alleles

Question 3

Explain how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the right aorta (5 marks):

Answer 3

1. Atrium has a higher pressure than the ventricles- causing AV valves to open
2. Ventricle has higher pressure than atrium, causing AV valves to close
3. Ventricle has higher pressure than aorta, causing SL valves to open
4. higher pressure in aorta than ventricle causing SL valves to close
5. Muscle contraction causes increase in pressure

Question 4

Describe the role of haemoglobin in the loading, transport and unloading of oxygen (5 marks):

Answer 4

1. He loads/ binds to oxygen in the lungs
2. At high partial pressure of oxygen
3. Binding of an oxygen molecule to Hb makes binding of another molecule of oxygen easier
4. Oxygen transported as oxyhemoglobin in red blood cells
5. Hb unloads/ dissociates oxygen in respiring cells/ tissues
6. At low partial pressures of oxygen

Question 5

Explain of tissue fluid is formed and how it may be returned to the circulatory system (6 marks):

Answer 5

1. Hydrostatic pressure of blood high at arterial end
2. Fluid/ water soluble molecules lass out
3. Proteins/ large molecules remain
4. Lowers the water potential/ becomes more negative
5. Water moves back into venous end of capillary by osmosis/ diffusion
6. Lymph system collects any excess tissue fluid which returns to blood/ circulatory system

Question 6

Describe and explain 4 ways in which the structure of a capillary is adapted for its function (4 marks):

Answer 6

• permeable capillary wall/ membrane
• single cell thick- reduces diffusion distance
• flattened endothelial cells, reduces diffusion distance
• fenestrations- allows large molecules through

Question 7

Describe how populations of Nm can become resistant to antibiotics (4 marks):

Answer 7

1. Mutation occurs
2. Results in cell with allele for resistance to antibiotic
3. Cell survives and passes the allele for resistance to offspring
4. Process repeated with different genes conferring resistance to each of the other two antibiotics

Question 8

Describe what happens to chromosomes in meiosis (6 marks)

Answer 8

1. Chromosomes condense
2. Chromosomes associate in their homologous pairs
3. Crossing over can occur
4. Join spindle fibres
5. At equator
6. By centromere
7. Homologous chromosomes move to opposite poles
8. Separation of pairs of sister chromatids in 2nd division

Question 9

How to reduce uncertainty (1 mark):

Answer 9

Use an instrument with smaller increments

Question 10

Why would a calorimeter improve repeatability? (1 mark)

Answer 10

Standardises the method

Question 11

Why is it not possible to determine the identity of the structures labelled x using an optical microscope? (2 marks)

Answer 11

• wavelength of light too long
• not a high enough resolution

Question 12

Describe the role of one named organelle in digesting bacteria (3 marks):

Answer 12

• lysosomes
• fuse with vesicles
• release hydrolytic enzymes

Question 13

What is a null hypothesis?

Answer 13

No significance between observed and expected data, results are down to chance

Question 14

Describe how humans breath in and out (5 marks):

Answer 14

BREATH IN:
1. Diaphragm muscles contract and diaphragm flattens
2. External intercostal muscles contract and ribcage pulled out
3. Volume increases and pressure decreases in the thoracic cavity to below atmospheric pressure
BREATH OUT:
4. Diaphragm muscles relax and diaphragm moves up
5. External intercostal muscles relax and ribcage moves down
6. Causes volume decrease and pressure increase in thoracic cavity to above atmospheric pressure

Question 15

Describe how natural selection may have led to all mammals in a population producing CEL (4 marks):

Answer 15

1. Mutation results in a new allele
2. Those with a new allele are able to digest triglycerides
3. Individuals with new allele are more likely to survive and reproduce
4. Directional selection
5. Increase in frequency of allele in population

Question 16

Name the type of blood vessel that controls blood flow to muscles and explain how these blood vessels change blood flow during exercise (3 marks):

Answer 16

1. Arterioles
2. Muscle relaxes
3. Vasodilation increases blood flow

Question 17

Give the pathway a red blood cell takes when travelling in the human circulatory system from the kidney to the lungs (3 marks):

Answer 17

1. Renal vein
2. Vena cava to right atrium
3. Right ventricle to pulmonary artery

Question 18

Explain how water from tissue fluid is returned to the circulatory system (4 marks):

Answer 18

1. Plasma proteins remain
2. Creates water potential gradient
3. Water moves to blood by osmosis
4. Returns to blood via lymphatic system

Question 19

Genome definition:

Answer 19

Complete set of genes in a cell

Question 20

Proteome definition:

Answer 20

Full range of proteins that a cell can produce

Question 21

Consider the accuracy and limitations of the early classification of bacteria using the arrangement of flagella (3 marks):

Answer 21

1. It cannot distinguish/ identify specific species
2. Optical microscope resolution too low
3. Flagella are fragile so broken easily

Question 22

Describe the role of ATP in the process of translation in protein synthesis (2 marks):

Answer 22

1. Provides energy
2. To form peptide bonds

Question 23

Two factors which might increase the frequency at which a mutation can occur (2 marks):

Answer 23

1. Ultraviolet light
2. Tobacco tar

Question 24

Describe how organisms are grouped in a phylogenic classification system (2 marks):

Answer 24

1. Hierarchy of groups with no overlaps
2. Grouped according to evolutionary origins

Question 25

Describe and explain the relationship between surface area to volume ratio of the human body and metabolic rate (3 marks)

Answer 25

1. As SA:V ratio increases, metabolic rate increases 2. Larger SA:V ratio loses more heat 3. Higher rate of respiration releases heat

Question 26

Two structural features of gills of a fish that increase their surface area (1 mark):

Answer 26

- gill lamellae - gill filaments

Question 27

What are microvilli?

Answer 27

Highly folded cell surface membrane