UNIT 2

Question 1

Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells.(4) 2020

Answer 1

1. DNA in nucleus is code (for protein);
2. Ribosomes/rough endoplasmic reticulum produce (protein);

Accept rER for ‘rough endoplasmic reticulum’

3. Mitochondria produce ATP (for protein synthesis);
4. Golgi apparatus package/modify;

OR

Carbohydrate added/glycoprotein produced by Golgi apparatus;

Accept body for ‘apparatus’

5. Vesicles transport OR Rough endoplasmic reticulum transports;
6. (Vesicles) fuse with cell(-surface) membrane;

Accept exocytosis at cell membrane

Question 2

Mark Scheme 2021 - Describe how a sample of chloroplasts could be isolated from leaves.

Answer 2

1. Break open cells/tissue and filter

OR Grind/blend cells/tissue/leaves and filter;

Accept homogenise and filter

2. In cold, same water potential/concentration, pH controlled solution;

Accept for ‘same water potential/ concentration’, isotonic

Accept for ‘pH controlled’, buffered

3. Centrifuge/spin and remove nuclei/cell debris;
4. (Centrifuge/spin) at high(er) speed, chloroplasts settle out;

Question 3

Name and describe five ways substances can move across the cell-surface membrane into a cell.

Answer 3

1. (Simple) diffusion of small/non-polar molecules down a concentration gradient;

If no reference to ‘small/ non-polar’ for 1.

accept this idea from ‘large/charged’ given in description of 2.

2. Facilitated diffusion down a concentration gradient via protein carrier/channel;

Reject if active rather than passive

3. Osmosis of water down a water potential gradient;
4. Active transport against a concentration gradient via protein carrier using ATP;
5. Co-transport of 2 different substances using a carrier protein;

For any answer accept a correct example

For ‘carrier protein’ accept symport OR cotransport protein