2022 paper 1

Question 1

In 6 markers what should you think about

Answer 1

ethical consequences from own knowledge, using graph, hazards, all steps

Question 2

why is thin layer of onion epidermis used

Answer 2

so only one layer of cells seen so it is easier to observe the individual cells

Question 3

why is iodine solytion added to epidermis

Answer 3

so easier to see (sub cellular structures e.g cell membrane, nucleus)

Question 4

why is cover slip lowered at an angle

Answer 4

to prevent air bubbles

Question 5

drawing of onion cells problems

Answer 5

connected lines, half cells drawn, do not shade in

Question 6

explain effect of damaging roots of tree

Answer 6

1-less absorption of water
-less water somlower rate of ohotosyn
-so less glucose produced
-for respiration
-so less cellulose produced and fewer cell walls made
-so fewer amino acids produced to make new proteins
-cells also lose turgidity

2-less absorption of ions
-nitrate ions so fewer proteins made for growth
-magnesium ions so less chlorphyll produced somlower rate of photosynthesis

3-damage to phloem
-less transport of sugars to root cells

4-damage to xylem
-less wtaer transported to cells
-fewer nitrates reach cells
-less chlorphyll produced…

5-less anchorage

Question 7

Describe how mitosis produces two gentically identical cells [4 MARKS]

Answer 7

-dna duplicated
-chromosomes are pulled apart
-cytoplasm divides in 2/cell membrane
-set of chromosomes are identical

Question 8

Why does an organsim with larger sa:vol have a higher metabolic rate

Answer 8

-higher sa:vol will lose heat more quickly
-requires higher rate of respiration
-respiration is part of metabolism
-need to generate more heat

Question 9

Explain how a vaccine for (HIV) could prevent a person developing HIV infection

Answer 9

-dead hiv sample injected into bloodstream
-white blood cells produce antibodies
-specific antibodies are produced quickly
-antibodies destroy hiv

Question 10

Describe how the monoclonal antibody for (hiv) is produced

Answer 10

-virus injected into mouse
-extract mouse lymphocytes that make specific antibody to hiv
-lymphocytes combined with tumour cell to create a hybridoma
-hybridoma cloned to create many cells that produce the antibody

Question 11

how would monoclonal antibody for hiv prevent person infected from developing aids

Answer 11

-monoclonal antibody is specfic to hiv
-mc antibodies attach to hiv antigens
-so hiv cannot bind to human cell and genetic material cannot enter human cell