Year 12 Mock AS 2023 Biology Paper 1

Question 1

Describe the primary structure of all proteins

Answer 1

1. Number and order of amino acids in a polypeptide chain
2. Joined by peptide bonds

Question 2

Define Universal, Non - Overlapping and Degenerate

Answer 2

1. Universal - Same codon always codes for same amino acid
2. Non overlapping - each base only part of one triplet
3. Degenerative - Triplet codes for more than one amino acid

Question 3

Describe how the appearance of the area containing DNS in a TEM image of a eukaryotic cell would differ from that shown in figure one

Answer 3

1. Nucleus
2. Nucleolus

Question 4

“Streptococcus” bacteria can infect the lungs when air is breathed in and cause lung disease

Describe the mechanism of breathing that causes ai2r to enter the lungs

Answer 4

1.Diaphram contracts and pulls down

2. External intercostal muscles contract
3. Volume of thoracic cavity increases and pressure decreases

Question 5

Suggest how “Streptococcus” bacteria with a thicker capsule are more likely to survive and cause lung disease

Answer 5

1. Less likely to bind to murein
2. Reduced phagocytosis so more bacteria growth

Question 6

On figure 2 draw a box around the R group of the fatty acid

Answer 6

1. A box around everything but the COOH group

Question 7

Explain why phospholipids can form a bilayer but triglycerides cannot

Answer 7

1. Phospholipids are both hydrophilic and hydrophobic
2. Triglycerides are only hydrophobic
3. Phosphate group in phospholipids attracts water

Question 8

Suggest why the fluidity of the membrane was higher after 4 months

Answer 8

1. Fatty acid A is saturated
2. At 4 months less fatty acid A more fatty acid B
3. Increase in fluidity caused by increased unsaturated fatty acids

Question 9

State one feature that shows in figure 5 were taken with an electron microscope and not an electron microscope

Answer 9

1. Name an organelle
2. Higher resolution as light has a longer wavelength

Question 10

Describe the role of tRNA in translation

Answer 10

1. Anticodon binds to codon
2. Amino acid brought to ribosome

Question 11

Block 1 3490, Block 2, 1200, Block 3, 3540, Block 4, 3530

Answer 11

1.Remove block 2 as anomaly
3490+3540+3530/3 = 3520

Question 12

Suggest what the student should have done when she saw that, shape C, block 2 was damaged

Answer 12

1. Repeated the experiment with an undamaged block

Question 13

State 3 variables the student should have controlled in order to obtain valid results

Answer 13

1 Same concentration of solution
2. Temperature
3. Same PH of solution

Question 14

Describe how gas exchange occurs in single celled organisms and explain why this method cannot be used in multicellular organisms

Answer 14

1. Gas exchange occurs by simple diffusion
2. In multicellular organisms the diffusion pathway is too long
3. Small organisms have larger SA:V

Question 15

Which components are found in human papilloma virus

Answer 15

1. Capsid and attachment protein

Question 16

Evaluate whether 10-12 year old boys should be given the HPV vaccine

Answer 16

1. Boys could pass virus on to girls
2. HPV vaccines could prevent some cancers in boys
3. Side effects unknown as well as dosage
4. Vaccination prevents HPV

Question 17

Describe the differences in prokaryotic biodiversity found in soil with these two farming methods

In your answer give the definitions of species richness and index of diversity

Answer 17

1. Species richness – number of species (in a
   community/habitat/ecosystem/area);
2. Index of diversity – the relationship between the
   number of species (in a community) and the
   number of individuals in each species;
3. No SD overlap for species richness
   so significant difference shown
   OR
   No SD overlap for species richness so difference
   not due to chance;
4. SD overlap so no significant difference in index
   of diversity
   OR
   SD overlap so any difference shown due to
   chance

Question 18

In recent years our knowledge of prokaryotic biodiversity in the soil has increased

Suggest why

Answer 18

1. DNA/genome sequencing now used;
2. (Now) can analyse every/more prokaryote
   species (in the community);
3. Rather than just recording
   measurable/observable characteristics

Question 19

give two precautions required when working with hydrochloric acid

Answer 19

1. Eye protection;
2. Gloves;
3. Add water to spills (immediately);
4. Do not pour away down sink;

Question 20

Another student compares the mitotic index in the roots of two different species
Give 2 considerations within her method to ensure this comparison is valid

Answer 20

1. Roots/plant of the same age;
2. Same growing conditions (for all roots);
3. Same distance from root tip;
4. Same time in acid
   OR
   Same temperature of acid;
5. Same concentration of acid;
6. Same pressure of squash;
7. Several fields of view (for each species);
8. Same time of day;

Question 21

Explain how sucrose transport proteins in leaf cells enable the production of a pressure gradient in the phloem

Answer 21

Pressure increase at source generated by:
1. Sucrose co-tranported into phloem
OR
Sucrose actively transported into phloem;
2. Causes decrease in water potential (inside
phloem);
3. Water enters by osmosis (into phloem);

Question 22

Potato plants with fewer sucrose transport proteins produce fewer potatoes and accumulate sugars in leaves

Explain why

Answer 22

1. Carbohydrates made by photosynthesis (in the
   leaf);
2. Less sucrose transported into phloem at
   leaf/source
   OR
   Less sucrose transported to sink/potato/root
   OR
   Less sugar stored as starch;

Question 23

Give two reasons why glucose uptake by muscle cells increases significantly during exercise

Explain your answers

Answer 23

1. Increased respiration;
2. To provide more ATP for muscle contraction;
3. (More glucose being used so) concentration
   gradient for glucose
   OR
   Increased numbers of glucose transporter
   proteins in the membrane;
4. (Glucose enters by) facilitated diffusion

Question 24

Which statement correctly describes the structure of both a sucrose transport protein and a glucose transport protein

Answer 24

The secondary structure is held by hydrogen
bonds.
The tertiary structure allows the protein to be
positioned spanning the whole cell membrane.