End Of Year 12 Exam

Question 1

What is the pathway taken by a protein that has been made and is to be secreted from a cell?

Answer 1

Ribosomes (can be on the RER) -> Vesicle -> Golgi apparatus -> Vesicle -> Plasma membrane

Question 2

What are the roles of the cytoskeleton?

Answer 2

• mechanical strength and structural role
• helps with movement
•transports organelles within cell

Question 3

What are the roles of the cytoskeleton in a human skin cell?

Answer 3

Providing mechanical strength to the cell and transport of organelles within the cell ( skin doesn’t move)

Question 4

What features are associated with a prokaryotic cell?

Answer 4

•cell walls made of peptiglygan
•extrachromosomal DNA that is circular
•70S ribosomes

Question 5

What is the correct description of polymers?

Answer 5

Some polymers are composed of several monomers that are similar in structure but not identical

Question 6

What elements are amino acids composed of?

Answer 6

• carbon
• hydrogen
• oxygen
• nitrogen

Question 7

What’s a description of the structure of cellulose?

Answer 7

Straight chains contain 1,4-glycosidic bonds

Question 8

What structure does a pyramidine have?

Answer 8

Simple structure - single (1) ring
• cytosine • thymine

Question 9

What structure does a purine have?

Answer 9

Complicated structure - more than one ring
• Adenine • Guanine

Question 10

What is different about ribose compared to deoxyribose?

Answer 10

Ribose has an OH group on Carbon 2

Question 11

What is the structure of ADP?

Answer 11

It is a nucleotide
Ribose with an adenine base on carbon 1 and 2 phosphate groups on carbon 4

Question 12

What is a hydrophyte and what’s an adaption of it?

Answer 12

A water-loving plant
It has many stomata on the upper surfaces of leaves s

Question 13

What makes alveoli an efficient gas exchange surface?

Answer 13

• they are very thin - short diffusion pathway
• they are close to the capillaries
• they are composed of a thin layer of flattened cells/ single layer of epithelium cells

Question 14

What’s the structure and function of a companion cell in the phloem?

Answer 14

• has a large nucleus as it is a very active cell
• contains lots of mitochondria which make ATP to force H+ ions out via active transport which then diffuse back in with sucrose from photosynthesis via co-transport
• they pick up sucrose from mesphoyll in leaf (source)
• life support for sieve tube

Question 15

What is the structure and function of the sieve tube element in the phloem?

Answer 15

• it is living cells and is long continuous tubes
• it lacks organelles making it easier for phloem sack to flow up and down without any restriction
• translocation occurs- mass flow of amino acids and sucrose - flows bidirectional from source to sink
• contains sieve plates which have holes to make the flow up and down unrestrictive
• has thin side walls which don’t contain lignin to help sucrose get into sieve tube

Question 16

Name and describe the reaction that produces amino acids from polypeptides?

Answer 16

Hydrolysis reaction - breaks peptide bonds between monomers

Question 17

How does cholesterol affect fluidity at different temperatures?

Answer 17

Cholesterol increases fluidity at low temps and decreases fluidity at high temps.

Question 18

Are ribosomes membrane-bound organelles?

Answer 18

No