Cell Specialisation

Question 1

Unicellular vs multicellular

Answer 1

Unicellular have a
- larger sa:v
- all cells are exposed to environment
- effective exchange surface for gases, nutrients amd waste
- all cells preform all functions (Mrs gren)

Multicellular opposites
Need specialised cells to preform different functions

Question 2

Definition of differentiation

Answer 2

When a cell becomes specialised to carry out a particular job function

Question 3

Categories of differentiation

Answer 3

Change in number of particular organelle
Change in shape of cell
Change in contents of cell

Question 4

How is a erythrocyte specialised for it function

Answer 4

Rbc- transports o2 around body and co2 to lungs
- biconcave shape = increase in SA more oxygen can be absorbed
- high amount of haemoglobin so more oxygen can bind
- no nucleus= more space for haemoglobin molecules
- elastic membrane allows cell to be flexible and change shape to squeeze through capillaries

Question 5

How is a neutrophil specialised for its function

Answer 5

Destroys pathogens by phagocytosis and the secretion of enzymes
- flexible shape
= can squeeze through cell junctions on the capillary wall
= allows them to form pseudopodia that engulf microorganisms
- large number of lysosomes= help digest and destroy invading cells
- lobed nucleus + flexible nuclear membrane helps cell to penetrate cell junction

Question 6

How is a sperm cell specialised for its function

Answer 6

To fuse with egg and pass on fathers genes
- haploid nucleus
- acrosome contains digestive enzyme that breaks down outer layer of egg
- mid piece packed with mitochondria to release lots of energy
- tail rotates to facilitate movement

Question 7

How is a palisade cell specialised for its function

Answer 7

Carry out photosynthesis
- large number of chloroplasts to maximise absorption of light
- tall and thin
= light can penetrate deeper before encountering another cell
= allows cells to be packed more densely

Question 8

How is a root hair cell specialised for its function

Answer 8

Absorption of water and minerals from the soil
- root hair increase SA so higher water uptake
- thinner walls = short diffusion path
- permanent vacuole = maintains water potential gradient
- mitochondria for active transport

Question 9

How is a guard cell specialised for its function

Answer 9

Control opening of stomata to regulate water loss and gas exchange
- inner cell walls are thicker and outer cell walls are thinner= allows cell to bend when turgid
- cytoplasm has high density of chloroplasts and mitochondria

Question 10

How is a ciliated epithelium specialised for its function

Answer 10

Moving substances across the surface of a tissue
- have cillia that beat in coordinated way to move material along the surface of the epithelium tissue
- goblet cells secrete mucus = traps dust, dirt and microorganisms, preventing them from entering organs and causing infection

Question 11

Describe how guard cells open

Answer 11

Only epidermal cell with chloroplasts
In daylight the stomata open so co2 can enter leaf making the chloroplasts carry out photosynthesis. The energy made from photosynthesis allows the guard cells to gain K+ ions through active transport. This lowers the water conc in the cell so water moves in via osmosis and the cells swell keeping stomata open