2.6.7 Specicalised Cells

Question 1

Specialised Cells

Answer 1

In complex multicellular organisms, eukaryotic cells become specialised for specific functions
These specialised eukaryotic cells have specific adaptions to help them carry out their function
For example, the structure of a cell is adapted to help it carry out its function (this is why specialised eukaryotic cells can look extremely different from each other)
Structural adaptions include:
- the shape of the cell
- the organelles the cell contains (or doesn’t contain)
For example:
- cells that make large amounts of proteins will be adapted for this function by containing many ribosomes (the organelle responsible for protein protein production)

Question 2

Erythrocytes (Red Blood Cells)

Answer 2

Function: transport oxygen around the body and carbon dioxide to the lungs
Adaptions: - they are biconcave in shape which increases the surface area over which oxygen can be absorbed
- the cytoplasm contains high amounts of the pigment haemoglobin which can readily bind to oxygen
- No nucleus is present which makes more space inside the cell for haemoglobin molecules for maximum oxygen-carrying capacity
Elastic membrane allows the cell to be flexible and change shape as it squeezes through narrow capillaries

Question 3

Neutrophils

Answer 3

Function: - destroys pathogens but phagocytosis and the secretion of enzymes
Adaptions: - neutrophils have a very flexible shape that allows them to squeeze through cell junctions in the capillary wall
- their flexibility also enables them to form pseudopodia (cytoplasmic projections) that engulf microorganisms
- there is a large number of lysosomes present in the cell which are digestive enzymes that help digest and destroy invading cells

Question 4

Sperm Cells

Answer 4

Function: - reproduction - to fuse with an egg, initiate the development of an embryo and pass on fathers genes
Adaptions: - the head contains a nucleus that contains half the normal number of chromosomes (haploid, no chromosomes pairs)
- the acrosome in the head contains digestive enzymes that can break down the outer layer of an egg cell so that the haploid nucleus can enter to fuse with the egg’s nucleus
- the mid-piece is packed with mitochondria to release energy (via induction) for the tail movement
- the tail rotates, propelling the sperm cell forwards and allowing it to move towards the egg

Question 5

Root Hair Cells

Answer 5

Function: - the absorption of water and mineral ions from soil
Adaptions: - root hair to increase surface area so the rate of water uptake by osmosis is greater (cash absorb more water no kid real ions than if the SA was lower)
- thinner walls than other plant cells so that water can move through easily (due to shorter diffusion distance/pathway)
- permanent vacuole contains cell sap which is more concentrated than soil water, maintaining a steep water potential gradient
- mitochondria for active transport of mineral ions
- remember that chloroplasts are not found in these cells - there’s no light for photosynthesis underground

Question 6

Ciliates Epithelium

Answer 6

Function: - moving substances across the surface of a tissue
Adaptions: - have cilla (hair-like structures), which beat in a coordinated way to shift material along the surface of the epithelium tissue
- goblet cells secrete mucus which helps to trap dust, dirt and microorganisms, preventing them from entering via tail organs where they might cause infection

Question 7

Squamous Epithelium

Answer 7

Function: - provide a surface covering or outer layer. Found on a variety of organs and structures e.g. blood vessels and alveoli
Adaptions: - squamous epithelium consists of a a single layer of flattened cells on a basement membrane
- the layers of cell forms a thin cross-section which reduces the distance that substances have to move to pass through - it shortens the diffusion pathway
- it is permeable, allowing for the easy diffusion of gases

Question 8

Palisade Cells

Answer 8

Function: - carry out photosynthesis to produce glucose and oxygen
Adaptions: - a large number of chloroplasts (the site of photosynthesis) are present in the cytoplasm to maximise the absorption of light for photosynthesis
- the tall and thin shape of the cell allows light to penetrate deeper before encountering another cell wall (cell walls absorb/reflect light) and for many cells to be densely packed together

Question 9

Guard Cells b

Answer 9

Function: - control the opening of the stomata to regulate water loss and gas exchange
Adaptions: - inner cell walls are thicker (those facing the air outside the leaf) while the outer walls are thinner (those facing adjacent epidermal cells). The difference in thickness of the cell walls allows the cell to bend when turgid
- the cytoplasm has a high density of chloroplasts and mitochondria. Scientists think that these organelles may play a role in the opening of the stomata