Topic 2

Question 1

Why does mitosis take place?

Answer 1

For growth or to replace damaged cells.

Question 2

What is interphase?

Answer 2

Mitochondria and ribosomes grow and duplicate their DNA.

Question 3

What are the 4 stages of mitosis?

Answer 3

1) Prophase- Chromosomes condense becoming thicker and membrane around the nucleus breaks down.
2) Metaphase- Chromosomes line up across the centre of the cell.
3) Anaphase- Chromosomes are pulled to opposite ends of the cell.
4) Telophase- The cell splits and clones to form another cell.

Question 4

1) What is cell differentiation?
2) What is cell elongation?

Answer 4

1) Where a cell becomes specialised for its job and allows the organism to work more efficiently.
2) It is how plants grow and is when a plant cell expands.

Question 5

What do the cerebrum, cerebellum and medulla do?

Answer 5

Cerebrum- Right cerebral hemisphere controls muscles on the left and vice versa. Movement, intelligence, memory, language and vision.
Cerebellum- Responsible for muscle coordination and balance.
Medulla- Controls unconscious activities like breathing and heart.

Question 6

What are the scanners used for brain investigation?

Answer 6

CT Scan:
- Makes an image of the brain and can help see disease or damage.

PET Scan:
- Use chemicals to see which parts of the brain are active.
- Can be used to see structure and function (which CT can’t).

Question 7

What is a synapse?

Answer 7

Connection between neurons and signal is transferred by chemicals called neurotransmitters which diffuse across the gap.

Question 8

How do reflexes help prevent injury?

Answer 8

Stimulation of pain»Impulse travels along sensory neuron»Impulses are passed along a relay neuron via a synapse»Impulse travels along the motor neuron via synapse»Impulse reaches muscle so it contracts avoiding as much damage.

Question 9

Why does short sightedness happen?

Answer 9

• Lens bends light too much so you can’t see things far away.
• Eyeball is too long.
• Concave/ divergent lens to correct it.

Question 10

Why does long sightedness happen?

Answer 10

• The lens doesn’t bend light enough so you can’t see things close up.
• Eyeball is too short.
• Convex lens to correct it.

Question 11

What happens when the eye focuses on close and far objects?

Answer 11

Close:
- Ciliary muscle contracts slackening the suspensory ligaments.
- Lens becomes more rounded to refract light more
Far:
- Ciliary muscle relaxes so suspensory ligament pulls tight.
- Pulls lens to a less rounded shape to refract light less.