Topic 1- cell division

Question 1

What are chromosomes made up of?

Answer 1

Chromosomes consist of DNA molecules combined with proteins. They contain genes which provide the instructions for protein synthesis

Question 2

What is a gene?

Answer 2

A section of DNA which codes for a protein

Question 3

How many chromosomes are found in the nucleus of human body cells?

Answer 3

46

Question 4

How many chromosomes are found in the nucleus of gametes?

Answer 4

23

Question 5

How are chromosomes arranged in the nucleus of a body cell?

Answer 5

Arranged in pairs - 46 chromosomes form 23 pairs

Question 6

What are the three main stages of the cell cycle

Answer 6

Interphase
Mitosis
Cytokinesis

Question 7

Why is mitosis important

Answer 7

produces identical cells which all have the same genetic Information
produces additional cells for growth and repair

Question 8

Describe the first stage of the cell cycle

Answer 8

Interphase- longest stage, cell grows and increase in mass, replicates DNA and synthesis more organelles

Question 9

Describe the second stage of the cell cycle

Answer 9

Mitosis- each chromosome in a pair is pulled to opposite poles of the cell, then the nucleus divides

Question 10

Describe the third stage of the cell cycle

Answer 10

Cytokinesis- The cytoplasm and cell membrane divide, two identical daughter cells are produced

Question 11

What is a stem cell

Answer 11

An unspecialised cell which is capable of differentiating into other cell types and of self-renewal

Question 12

What is the function of stem cells in embryos

Answer 12

Embryonic stem cells can replicate themselves and differentiate into many other types of cells. Embryonic stem cells may be able to treat conditions such as paralysis and diabetes by dividing to replace damaged cells

Question 13

What is the function of stem cells in adult bone marrow?

Answer 13

adult stem cells can differentiate into several cell types to replace dead or damaged tissues.

Question 14

What is the function of stem cells in plant meristems

Answer 14

Meristem stem cells retain the ability to differentiate into any type of plant cell throughout their lifespan- they can differentiate into any cell which is required by the plant

Question 15

What is therapeutic cloning?

Answer 15

A cloning method where an embryo is produced with the same genetic makeup as the patient
the stem cells which originate from the the embryo will not be rejected by the patients immune system, so can be used to treat certain medical conditions

Question 16

What are the advantages of cloning plants using meristem stem cells?

Answer 16

can prevent rare plants from becoming extinct
can produce large numbers of plants with a favourable characteristics
can produce identical plants for research

Question 17

What are issues associated with the use of stem cells

Answer 17

many embryonic stem cells are sourced from aborted embryos - some people have an ethical/religious objection
development of stem cell therapies is slow, expensive and difficult
adult stem cells infected with viruses could transfer infections to patients
if donor stem cells do not have a similar genetic makeup to the patient, an immune response could be triggered,