Cell Biology

Question 1

Name 2 pieces of laboratory equipment you could use to prepare cells to view using a microscope.

Answer 1

Any two from:
* Slide
* Cover slip
* Scalpel
* Tweezers
* Pipette
* Dye/stain (e.g. methyl blue)

Question 2

Red blood cells are specialised animal cells.
Compare the structure of a red blood cell with the structure of a plant cell. [6 marks]

Got 4/6 during test on 24th March

Answer 2

Differences:
* red blood cell has no nucleus or plant cell has a nucleus
* red blood cell has no cell wall or plant cell has a cell wall
* red blood cell is a biconcave disc or there are many different shapes of plant cell
* red blood cell contains haemoglobin or plant cells do not contain haemoglobin
* red blood cells do not contain chlorophyll or plant cells (may) contain chlorophyll
* red blood cell has no chloroplasts or plant cell has chloroplasts
* red blood cell has no (permanent) vacuole or plant cell has (permanent) vacuole
* red blood cells are (much) smaller than plant cells

Similarities:
both have
* cytoplasm
* cell membrane
* pigments (although they are different)

ignore references to mitochondria and ribosomes

Level marked - 2 levels

Question 3

Explain the financial impact on the UK economy of an increasing number of people who are obese. [2 marks]

Answer 3

costs the NHS / UK health service / Government / hospitals more money (because need to pay for)
additional surgery / medication / hospital stay to treat stroke / diabetes
or
more time off work (if in hospital / unwell) (1) (so) employer / Government have to give financial support (1)

Question 4

A person who eats a diet high in saturated fat might become obese.
Name two health conditions that might develop if a person eats a diet high in saturated fat. [2 marks]

Got 1/2 during test on 24th March

Answer 4

type 2 diabetes

CVD / CHD
or
heart attack / disease
or
stroke

Question 5

Describe how a student could extend their investigation to determine the effect of a factor other than temperature on amylase activity. [2 marks]

Got 1/2 during test on 24th March, slightly altered wording

Answer 5

Keep temperature constant (but) change named factor (e.g. pH) and test a range of values of the named factor.

Question 6

Compare the structure and function of xylem tissue and phloem tissue. [6 marks]

Got 4/6 during text on 24th March

Answer 6

Structure
* xylem is made of dead cells and phloem is made of living cells
* phloem cells have pores in their end walls and xylem cells do not have pores in their end walls
* xylem is hollow or xylem does not contain cytoplasm and phloem contains cytoplasm
* xylem contains lignin and phloem does not (contain lignin)
* both made of cells
* both tubular

Function
* xylem transports water / mineral ions and phloem transports (dissolved) sugars
* xylem is involved in transpiration and phloem is involved in translocation
* xylem transports unidirectionally and phloem transports bidirectionally
* both transport liquids / substances throughout the stem / leaves / roots / plant

Level marked - 2 levels
For Level 2, students must refer to both structure and function of
xylem and phloem tissue.

Question 7

Some types of cancer can cause the numbers of blood components in a person’s
body to fall to a dangerously low level.
A person with one of these types of cancer may experience symptoms such as:
* tiredness
* frequent infections
* bleeding that will not stop after the skin is cut.
Explain how a very low number of blood components in the body can cause
these symptoms. [6 marks]

Got 4/6 in text on 24th March

Answer 7

Tiredness
* fewer red blood cells
* so less haemoglobin
* so less oxygen transported around the body
* so less (aerobic) respiration can take place
* so more anaerobic respiration takes place
* less energy released for metabolic processes or less energy released so organs cannot function as well
* lactic acid produced (during anaerobic respiration) causes muscle fatigue

Frequent infections
* fewer white blood cells / phagocytes / lymphocytes
* so fewer antibodies produced or less phagocytosis
* so fewer pathogens / bacteria / viruses killed

Bleeding
* fewer platelets
* so blood does not clot as easily

Level marked - 3 levels
For Level 3, reference to all three symptoms must be made.