Specialised cells in multicellular organisms

Question 1

What is the process called which cells become specialised?

Answer 1

Differentiation

Question 2

What are Erythrocytes?

Answer 2

Red blood cells

Question 3

Describe an Erythrocyte.

Answer 3

-Small around 7.5 micrometres, barely fitting into capillaries
-Biconcave shape for large surface area for gas exchange
-No nucleus, mitochondria or endoplasmic reticulum, so more haemoglobin can be packed

Question 4

What are Neutrophils?

Answer 4

White blood cell

Question 5

Describe a Neutrophil.

Answer 5

-Function is to ingest pathogens by phagocytosis
-Multilobed nucleus so they can squeeze out of capillaries and into wounded or infected tissues
-Specific receptor proteins in cell surface membranes that bind to antigens on pathogens

Question 6

What is Epithelium?

Answer 6

“lining” tissue

Question 7

Describe Squamous Epithelial cells?

Answer 7

-Flat in shape: Short diffusion distance
-Often permeable: Small molecules can pass quickly through membranes

Question 8

Describe Ciliated Epithelial cells?

Answer 8

-Work with goblet cells to clear pathogens and dirt from the trachea, bronchi and bronchioles

Question 9

How do Goblet and Ciliated Epithelial cells work together?

Answer 9

-Goblet cells secrete mucus which traps pathogens and dirt.
-Ciliated epithelial cells waft cilia to move mucus towards the oesophagus to be swallowed.

Question 10

Describe a Sperm cell.

Answer 10

-Many mitochondria for rapid aerobic respiration for ATP
-Tail gives motility so it can move towards an ovum
-Acrosome is a specialised lysosome containing hydrolytic enzymes to digest layer of ovum
-Head contains haploid nucleus for fertilisation

Question 11

Describe a Palisade cell.

Answer 11

-Long and cylindrical, for maximum light absorption
-Large vacuole so chloroplasts are positioned near outside, reducing diffusion distance
-Contain many chloroplasts
-Chloroplasts moved by cytoskeleton near to upper surface of leaf when light intensity is low and away when its high.

Question 12

Describe a Guard cell?

Answer 12

-Stoma is open when guard cell is turgid and closed when flaccid

Question 13

How do stoma close?

Answer 13

-Actively transport K+ out
-H2O follows K+ by osmosis down water potential gradient
-Guard cell becomes flaccid
-Stoma closes

Question 14

Describe a Root Hair cell?

Answer 14

-Function is to take mineral ions and water from soil
-Ions actively transported
-Many mitochondria to produce ATP for active transport
-High surface area, increasing rate of ion and water uptake