Topic 1 - Cell biology: Cell Division

Question 1

(a) Name the structures inside the cell nucleus that contain DNA.

Answer 1

chromosomes

Question 2

(c) What type of substances are labelled A, C, G and T in Figure 1?

Answer 2

base

Question 3

What type of substance does a gene code for?

Answer 3

protein

Question 4

(h) What is the name of the type of cell division that produces sperm cells?

Answer 4

meiosis

Question 5

Name the chemical which the genetic material is made from.

Answer 5

DNA

Question 6

Explain how a transplant of bone marrow cells can help to treat medical
conditions. (2)

Answer 6

(g) (bone marrow) cells differentiate into many / other types of (named) cell

will cure diseases where cells are damaged

Question 7

(a) Describe three differences between the processes of mitosis and meiosis.

Answer 7

Answers must be comparative:

mitosis produces two (daughter) cells but meiosis produces
four (daughter) cells

• one cell division in mitosis but two cell divisions in meiosis

mitosis produces genetically identical cells, but meiosis
produced genetically different cells

mitosis produces diploid cells but
meiosis produces haploid cells

Question 8

(b) Describe one similarity between the processes of mitosis and meiosis.

Answer 8

• DNA doubles / copies / replicates (once)
  increase in number of mitochondria

Question 9

(a) Define the term double circulatory system.

Answer 9

blood is pumped to the lungs by one / right side of the heart
and
blood is pumped to the body by the other / left side of the heart

Question 10

Explain why having only one ventricle makes the circulatory system less
efficient than having two ventricles. 2 marks

Answer 10

oxygenated and deoxygenated blood mixes

(so) less oxygen reaches the body / tissues / cells

Question 11

(d) Explain why an axolotl may die in water with a low concentration of oxygen. 4 marks

Answer 11

concentration gradient (of oxygen) is shallow(er) / less steep

(therefore) less oxygen diffuses into blood / cells / gills

so oxygen diffuses out of axolotl’s blood
/ cells / gills

(so) less (aerobic) respiration occurs so less energy is released

anaerobic respiration occurs, lactic acid is produced which is toxic

Question 12

(f) Name one condition that could be treated using regenerated human tissue.

Answer 12

paralysis
* diabetes

Question 13

Suggest two other advantages of asexual reproduction

Answer 13

faster
many offspring produced

Question 14

(4)Explain why sexual reproduction is an advantage

Answer 14

genetic variation
better adapted survive
can escape adverse event in original area
many offspring so higher probability some will survive

Question 15

(a) What is a stem cell? 2

Answer 15

unspecialised cell

that can differentiate (many) other cell types

Question 16

(b) Give one way a malignant tumour differs from a benign tumour.

Answer 16

invade / spread to other tissues via the blood (benign don’t)

or form secondary tumours

Question 17

Name two other substances the cells need so they can grow and divide.

Answer 17

glucose
amino acid

Question 18

Give two advantages of using the stem cell trachea compared with a
trachea from a dead human donor.

Answer 18

no need to wait for a donor

(so) no risk of rejection

Question 19

Suggest how a stent in the trachea helps to keep the patient alive.

Answer 19

stent opens up the trachea
1
allowing air to flow through

Question 20

Evaluate the use of stem cells from a patient’s own bone marrow instead of
stem cells from an embryo. 6

Answer 20

embryos advantages
* can create many embryos in a lab
* painless technique
* can treat many diseases / stem cells can become any type of cell
but harm / death to embryo

bone marrow advantages
* no ethical issues / patient can give permission
* can treat some diseases
* procedure is (relatively) safe / doesn’t kill donor

but rejection or infection
* can only treat a few diseases

Question 21

cell division for bacteria

Answer 21

binary fission

Question 22

Why would it not be possible to treat a genetic disorder in a child
using his own umbilical cord stem cells?

Answer 22

(iv) stem cells have same faulty gene / allele / DNA / chromosomes

Question 23

Describe how mycoprotein is produced. 4

Answer 23

fungus / Fusarium

with glucose (syrup)

in aerobic conditions or in presence of oxygen

mycoprotein is harvested / purified