Cell Specialisation

Question 1

What is cell specialisation?

Answer 1

cells undergoing differentiation; a process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role
Cells can either differentiate once early on or have the ability to differentiate their whole life (these are called stem cells).
In animals, most cells only differentiate once, but in plants many cells retain the ability.

Question 2

Examples of specialised cells in animals

Answer 2

-sperm cells
-nerve cells
-muscle cells

Question 3

Sperm cell description

Answer 3

-streamlined head and long tail to aid swimming
-many mitochondria which supply the energy to allow the cell to move
-the acrosome (top of head) has digestive enzymes which break down the outer layers of membrane of the egg cell

Question 4

Sperm cell function

Answer 4

to get male DNA to the female DNA

Question 5

Sperm cell specialisation

Answer 5

specialised to carry the male’s DNA to the egg cell (ovum) for successful reproduction

Question 6

Nerve cells description

Answer 6

-long axon, enabling the impulses to be carried along long distances
-has lots of extensions from the cell body (dendrites) means branches connections can form with other nerve cells
-nerve endings have many mitochondria which supply the energy to make special transmitter chemicals called neurotransmitters. These allow the impulse to be passes from one cell to another.

Question 7

Nerve cell specialisation

Answer 7

specialised to transmit electrical signals quickly from one place in the body to another

Question 8

Muscle cells description

Answer 8

-special proteins (myosin and actin) slide over each other, causing the muscles to contract.
-lots of mitochondria to provide energy from respiration for contraction
-they can store a chemical called glycogen that is used in respiration by mitochondria

Question 9

Muscle cells specialisation

Answer 9

specialised to contract quickly to move bones (striated muscle) or simply to squeeze (smooth muscle, e.g found in blood vessels so blood pressure can be varied), therefore causing movement

Question 10

Specialised cells in plants

Answer 10

-root hair cells
-xylem cells
-phloem cells

Question 11

Root hair cells description

Answer 11

-have a large surface area due to root hairs, meaning more water can move in
-the large permanent vacuole affects the speed of movement of water from the soil to the cell
-mitochondria to provide energy from respiration for the active transport of mineral ions into the root hair cell

Question 12

Root hair cell specialisation

Answer 12

specialised to take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots

Question 13

Xylem cells description

Answer 13

-upon formation, a chemical called lignin is deposited which causes the cells to die. They become hollow and are joined end-to-end to form a continuous tube so water and mineral ions can move through
-Lignin is deposited in spirals which helps the cells withstand the pressure from the movement of water

Question 14

Xylem cells specialisation

Answer 14

specialised to transport water and mineral ions up the plant from the roots to the shoots

Question 15

Phloem cells description

Answer 15

-cell walls of each cell form structures called sieve plates when they break down, allowing the movement of substances from cell to cell
-despite losing many sub-cellular structures, the energy these cells need to be alive is supplied by the mitochondria of the companion cells

Question 16

Phloem cells specialisation

Answer 16

specialised to carry the products of photosynthesis (food) to all parts of the plants