biology exam style questions

Question 1

state two differences between prokarytic and eukaryotic cells (2 marks)

Answer 1

• prokaryotic cells have no nuclues whilst eukaryotic cells do.
• prokaryotic cells have smaller ribosomes (70s ribosomes) whilst eukaryotic cells have larger ribosomes (80s ribosomes)

Question 2

describe the role of the cell membrane (2 marks)

Answer 2

• regulates movement of substances in and out of the cell
• provides protection and maintains the integrity of the cell

Question 3

one reason why light microscopes are very limited in what we can see through them (1 mark)

Answer 3

this is because the wavelength if light is the limiting factor.

Question 4

state two things that plasma membranes have embedded in them (2 marks)

Answer 4

*protein
*cholesterol

Question 5

what is the importance of plasma membranes having proteins in them (2 marks)

Answer 5

*the proteins act as receptors
*this means that the cell can respond to the external environment of the cell

Question 6

when can centrioles be found in isolation (2 marks)

Answer 6

when in the basal regions of flagella and cilia

Question 7

where are root hair cells located

Answer 7

can be found in the epithelium close t the root tip where there is no thickening

Question 8

explain why mitochondria are only maternally inherited (4 marks)

Answer 8

this is because the mitochondria from the mother are in the egg cell so remain when the nuclei of the sperm and egg cell fuse and divide but the mitochondria from the father are in the tail of the sperm which never enters the egg cell.

Question 9

explain why ciliated columnar epithelium cells contain many mitchondria (4 marks)

Answer 9

the main function of cilia is to move mucus away from the lungs and moving cilia requires lots of energy. mitochondria release energy which is stored in ATP so the cells have lots of mitochondria because lots of energy is needed to keep cilia moving all the time.

Question 10

explain the development of atherosclerosis (6marks)

Answer 10

• at first there is damage to the endothelial tissue lining of artery and this can be caused by smoking or high blood pressue
• this cause ldl cholesterol to build up in the wall of the arteries
• which results in inflammation as white blood cells move to the artery wall
• plaque forms also known as an atheroma due to white blood cells being in the artery walls as well as ldl cholesterol and calcium salts
• this narrows the artery and blood flow is restricted due to loss of elasticity
• this causes raised blood pressure