2015 Unit 2

Question 1

What is the function of the coronary arteries

Answer 1

• Carry oxygen/glucose

* To heart muscle/ tissue/ myocytes

Question 2

The rise and fall in blood pressure in the aorta is greater than in the small arteries. Suggest why.

Answer 2

Aorta 
• Is directly linked to the heart 
• Pressure is very high 
• Aorta has elastic tissue 
• Aorta has stretch/recoil

Question 3

Give two ways in which the structure of starch is similar to cellulose

Answer 3

Both
• Are polymers/polysaccharide
• Contains glucose/carbon, hydrogen and oxygen
• Contains glycosidic bonds 
• Have 1-4 links
• Hydrogen bonding within structure

Question 4

Give two ways in which the structure of starch is different from cellulose

Answer 4

Starch
• Contains alpha glucose
• Helical/coiled/compact/branched/not straight
• 1,6 bonds
• Glucose/monomers same way up
• No H-bonds between molecules
•No (micro) fibers/fibrils

Question 5

Suggest and explain one other way in which sieve cells are adapted for mass transport.

Answer 5

• Few organelles
• Cytoplasm at the edge
• Hollow/ Large vacuole/ Large space/Thick walls
• More flow/ Thick strong walls resist pressure

Question 6

Suggest and explain one other way in which companion cells are adapted for the transport of sugars between cells.

Answer 6

• Mitochondria releases energy/ATP/Site of respiration
• For active transport/uptake against concentration gradient
• Ribosomes/Rough Endoplasmic Reticulum produces proteins
• Proteins linked to transport eg. carrier proteins/ enzymes

Question 7

Describe the role of DNA polymerase in DNA replication.

Answer 7

• Joins nucleotides (to form new strand)

Question 8

Other than being smaller, give two ways in which prokaryotic DNA is different from
eukaryotic DNA.

Answer 8

Prokaryotic DNA
• Circular/non-linear DNA
• Not associated with proteins/ histones
• No introns

Question 9

Humans and grasshoppers have very similar percentages of each base in their DNA but
they are very different organisms.

Use your knowledge of DNA structure and function to explain how this is possible

Answer 9

• Have different genes
• Triplets are in different order/sequence
• So different amino acid coded for/ different protein/different polypeptide/ different enzyme

Question 10

The DNA of the virus is different from that of other organisms

Use your knowledge of DNA to suggest what this difference is. Explain your answer

Answer 10

Virus DNA
• A does not equal T/ C does not equal G
• So no base pairing
• So DNA is not doubled stranded/ single stranded

Question 11

Give three ways in which courtship behaviour increases the probability of successful
mating.

Answer 11

• Recognise same species
• Stimulates release of gametes
• Recognition to opposite sex
• Indication of sexual maturity
• Formation of a bond between two organisms (to have young)

Question 12

The events that take place during interphase and mitosis lead to the production of two
genetically identical cells. Explain how.

Answer 12

• DNA replicated
• Involving complementary base pairing
• Chromosomes line up along middle of the cell
• Sister chromatids are separated
• Each chromatid is separated to opposite poles

Question 13

The student cut thin sections of tissue to view with an optical microscope.
Explain why it was important that the sections were thin.

Answer 13

• To allow more light through

* A single/ few layer(s) to be viewed

Question 14

A mutation can lead to the production of a non-functional enzyme. Explain how

Answer 14

• Change/mutation in base sequence
• Change in primary structure (of enzymes)
• Change in hydrogen/disufide/ ionic bonds
• Change in tertiary structure
• Change in active site
• Substrate not complementary/ no enzyme-substrate complexes form

Question 15

Explain why tumour area may not be the best indicator of tumour size and suggest a
more reliable measurement.

Answer 15

• Area does not take into account the depth
• Tumours are 3-D and not 2-D
• Measure tumour volume/mass/weight

Question 16

Another group of scientists is currently using cancer drugs in the human trials. However, the
control group is not being given a placebo.

Suggest why a placebo is not being given and what is being given to this group instead

Answer 16

• Unethical not to treat patients

* Use normal cancer drugs/treatment