Biology

Question 1

Where are chromosomes found?

Answer 1

Nucleus

Question 2

What is the name of a section of a chromosome that controls characteristics?

Answer 2

Gene

Question 3

Which stage of the cell cycle takes the longest time?

Answer 3

Copying of chromosomes

Question 4

Which cell structure provides the most energy?

Answer 4

Mitochondria

Question 5

Why is mitosis important in living organisms?

Answer 5

To repair tissue

Question 6

What enzyme is produced by the salivary glands?

Answer 6

Amylase

Question 7

/. /. /
/ /. /
/. / /
/__/___/ why would a structure like this be best adapted for diffusion in or out of a cell

Answer 7

As there is a large surface area, to maximise diffusion and transport efficiency.

Question 8

Explain how a salivary gland is adapted to produce an enzyme.

Answer 8

it has many ribosomes to make proteins like enzymes. It also has many mitochondria to release energy for enzyme production.

Question 9

Evaluate the use of embryonic stem cells against the use of adult bone marrow.

Answer 9

Embryonic stem cells are totipotent, so they can differentiate into any cell type and treat many diseases. However, using them is unethical to some, as it involves destroying embryos.
Adult stem cells from bone marrow are multipotent and used to treat blood diseases. But the transplant weakens the immune system, increasing the risk of infection.
In conclusion, embryonic stem cells have more potential, but adult stem cells are safer, proven, and more ethically accepted.

Question 10

A cell has 8 chromosomes. If the cell divides by mitosis, how many chromosomes will each new cell contain?

Answer 10

8

Question 11

A plant cell swells up when put in water. Why?

Answer 11

Water moves into the plant cell by osmosis through a partially permeable membrane,
because the inside of the cell has a lower water concentration than the water outside
This causes the cell to swell and become turgid, but it does not burst because of the cell wall

Question 12

Why would an animal cell burst when put into water, but a plant cell wouldn’t?

Answer 12

Plant cells have a cell wall, while animal cells only have a cell membrane.

Question 13

Describe and explain how villi are adapted to maximise the rate of absorption.

Answer 13

• Large surface area due to finger-like shape and microvilli
• Thin walls for short diffusion distance
• Good blood supply to maintain concentration gradient
• Lots of mitochondria for energy in active transport

Question 14

What is the balanced equation for photosynthesis?

Answer 14

6 CO2 + 6 H2O → C6H12O6 + 6 O2

Question 15

How do guard cells assist photosynthesis?

Answer 15

Guard cells control the opening and closing of stomata. This allows carbon dioxide to enter the leaf for photosynthesis and reduces water loss when necessary

Question 16

How do palisade cells assist photosynthesis?

Answer 16

Palisade cells have lots of chloroplasts to absorb sunlight for photosynthesis. They are near the top of the leaf, so they receive the most sunlight

Question 17

Give three ways glucose is used in plants.

Answer 17

• Stored as insoluble starch
• Converted into cellulose to strengthen cell wall
• Makes proteins for growth

Question 18

Why does a plant photosynthesise less on a cloudy day than on a sunny day?

Answer 18

There is less light on a cloudy day, so the rate of photosynthesis is lower and the plant uses less carbon dioxide.

Question 19

What mineral ion is lacking when a plant turns yellow?

Answer 19

Magnesium ions

Question 20

Give 2 control variables in a pondweed experiment.

Answer 20

• Light intensity
• CO2 concentration

Question 21

What two measurements would the student make to calculate the rate of photosynthesis?

Answer 21

• Number of bubbles
• Time taken

Question 22

What is the limiting factor on the diagonal before the curve of a temperature-rate graph?

Answer 22

Temperature

Question 23

What is the limiting factor on the flat of a temperature-rate graph?

Answer 23

Carbon dioxide

Question 24

Name 3 enzymes.

Answer 24

• Amylase
• Protease
• Lipase

Question 25

Explain how lipase breaks down lipids.

Answer 25

lipase breaks down lipids and they are mainly broken down in the small intestine

Question 26

In a lipase pill, why would the lipase in the bead not digest the lipid coating of the pill?

Answer 26

Because they are dry

Question 27

If lactase works best at pH 8, explain why 'lactase is normally produced in the stomach of mammals' is not true.

Answer 27

The stomach is acidic, but Table 1 shows lactase works best at pH 8, which is alkaline.This means lactase is unlikely to be produced in the stomach.

Question 28

Describe the effect of temperature on an enzyme (lactase).

Answer 28

As temperature increases from 30°C to 45°C, the time taken to digest lactose decreases, showing that lactase works faster.This is because higher temperatures increase the rate of enzyme activity.However, above 45°C the time increases again, as the enzyme begins to denature, reducing its activity.

Question 29

How does bile help the digestion of milk?

Answer 29

Bile neutralises stomach acid, creating alkaline conditions in the small intestine.This provides the optimum pH for enzymes like lactase to work effectively.