P2 - 2018

Question 1

Which plant structure fits this statement:

Has stacked membranes arranged in parallel and contains DNA

Answer 1

chloroplast

Question 2

Which plant structure fits this statement:

Is made of polysaccharide

Answer 2

cell wall

Question 3

Which plant structure fits this statement:

Is an organelle and is not surrounded by two membranes

Answer 3

Golgi apparatus

Question 4

Human breast milk is produced + secreted by gland cells which have adaptations that include many mitochondria and many Golgi vesicles.

The milk contains a high concentration of protein.

Explain the role of these cell adaptations in the production and secretion of breast milk

Answer 4

Many mitochondria release energy for synthesis of protein

Many Golgi vesicles transport protein to cell membrane

Question 5

Describe how a peptide bond is formed between two amino acids to form a dipeptide

Answer 5

Condensation reaction (a loss of water) Between COOH

Question 6

The secondary structure of a polypeptide is produced by bonds between amino acids.

Describe how

Answer 6

Hydrogen bonds Between NH group of one amino acid and C=O group

Question 7

Two proteins have the same number and type of amino acids but different tertiary structures

Explain why

Answer 7

Different sequence of amino acids

Forms ionic bonds in different places

Question 8

Describe the relationship between size and surface area to volume ratio of Explain why oxygen uptake is a measure of metabolic rate in organisms

Answer 8

As size increases, ratio of surface area to volume decreases

Question 9

Explain why oxygen uptake is a measure of metabolic rate in organisms

Answer 9

Oxygen used in respiration which provides energy

Question 10

The scientist used units of μmol g−1 h−1 for the rate of oxygen uptake.

Suggest why he used μmol in these units

Answer 10

Measures small volume of oxygen uptake

Question 11

The scientist used the ratio of surface area to mass, rather than the ratio of surface area to volume.

Suggest 1 practical advantage of measuring the masses of frog eggs, tadpoles and
adults, compared with measuring their volumes.

Answer 11

more accurate in measuring mass

or

Causes less damage to animal to measure mass

Question 12

Give two similarities in the movement of substances by diffusion and by osmosis

Answer 12

Movement from high concentration to low concentration

not active processes

Question 13

What is the name given to the division of cytoplasm during the cell cycle?

Answer 13

Cytokinesis

Question 14

Describe + explain what a student should do when counting cells to make
Binary fission Cytokinesis Phagocytosis Segregation
sure that the mitotic index he obtained for this root tip was accurate

Answer 14

Repeat count to ensure figures are correct

Question 15

What is digestion?

Answer 15

Hydrolysis of large substances to smaller soluble substances

Question 16

Endocellulases and exocellulases act at different places on cellulose molecules

Suggest why

Answer 16

Active sites are different shapes so different enzyme-substrate complexes are formed

Question 17

The scientist used the same concentration of endocellulase and exocellulase in the mixtures. The rate of digestion of cellulose is greatest when both enzymes are present.

Suggest why.

Answer 17

Endocellulase increases surface area for exocellulase to digest

Question 18

What is the equation for calculating the percentage loss in mass?

Answer 18

initial Mass − Final Mass
———————————– x100
Initial Mass

Question 19

Suggest and explain one reason why bacteria resistant to tetracycline are more
common than bacteria resistant to streptomycin in these farm animals.

Answer 19

Tetracycline used in higher doses making resistant bacteria more likely to pass on gene for resistance

Question 20

In recent years, these farm animals have not been given tetracycline in their food. Despite this, the percentage of bacteria resistant to tetracycline has remained constant

why?

Answer 20

Bacteria pass on resistance gene when they reproduce

Question 21

Compare and contrast the DNA in eukaryotic cells with the DNA in prokaryotic cells

(5)

(2 compare, 3 contrast)

Answer 21

• Nucleotide structure is identical
• Nucleotides joined by phosphodiester bond
• DNA in mitochondria have similar structure to DNA in prokaryotes
• Eukaryotic DNA is longer
• Eukaryotic DNA is linear, prokaryotic DNA is
  circular

Question 22

Haemoglobins are chemically similar molecules found in many different species.
Differences in the primary structure of haemoglobin molecules can provide evidence of phylogenetic (evolutionary) relationships between species.

Explain how
(5)

Answer 22

• Mutations change nucleotide sequence
• Causing change in amino acid sequence
• Mutations build up over time
• More mutations in nucleotide sequence between distantly related species
• Distantly related species have earlier common ancestor