Cells, Organs And Life Processes

Question 0

How are guard cells adapted to open and close pores?

Answer 0

1. Special kidney shape which opens and closes the stomata
2. When the plant has lots of water the guard cells fill with it and go plump and turgid which makes the stomata open so gases can be exchanged for photosynthesis
3. When the plant is short of water the guard cells lose water and become flaccid making the stomata close.
4. Thin outer walls and thickened inner walls make the opening and closing work
5. They’re sensitive to light and close and night to save water loss without photosynthesis
6. You usually find more stomata ok the undersides if leaves than on top because the lower surface is shaded and cooler.

Question 1

How are palisade leaf cells adapted for photosynthesis?

Answer 1

1. Packed with chloroplasts for photosynthesis (more at top of cell)
2. Tall shape means a lot of surface area exposed down the side for absorbing CO2
3. Thin shape means you can pack loads of them at the top of the leaf

Question 2

How are red blood cells adapted to carry oxygen?

Answer 2

1. Concave shape gives a big surface area and helps them pass smoothly inside capillaries.
2. Packed with haemoglobin which is a pigment that absorbs oxygen
3. No nucleus which leaves them more room for haemoglobin

Question 3

How are egg cells specialised for reproduction?

Answer 3

1. Egg cell contains huge food reserves to feed the embryo

2. Eggs membrane instantly changes after fertilisation and stops any more sperm from entering

Question 4

How are sperm cells specialised for reproduction?

Answer 4

1. Long tail
2. Streamlined head
3. Mitochondria
4. Enzymes to digest egg cell membrane