Gcse Biology Paper 1 Cell Division & Stem Cells

Question 1

Why is Mitosis important?

Answer 1

-helps organisms grow in size and repair damaged tissue.

Question 2

what are the three main stages of the cell cycle?

Answer 2

• growth
• DNA replication+ mitosis
• Division (cytokinesis)

Question 3

What happens in the first stage of the cell cycle?

Answer 3

• the cell grows in size
• At the same time increases the number of sub-cellular structures (eg mitochondria, ribosomes)
• The DNA is duplicated
• each cell has full set of DNA

Question 4

Where are chromosomes found?

Answer 4

The nucleus

Question 5

What are are chromosomes ?

Answer 5

Chromosomes are string-like structures located inside the nucleus of animal and plant cells.

Question 6

What’s the chromosome made up of?

Answer 6

The long string like structure that makes up a chromosome is made up of a chemical called deoxyribonucleic acid (DNA)

Question 7

How many chromosomes do body cells contain?

Answer 7

• Human body cells contain 23 pairs of chromosomes

- In total 46

Question 8

What do chromosomes carry?

Answer 8

Chromosomes carry a large amount of genes which determine many of our features

Question 9

What is a gene?

Answer 9

A gene is a section of DNA that codes for proteins

Question 10

What happens in the first stage of the cell cycle?

Answer 10

-in the first stage the DNA replicates to
form two copies of each chromosome.

-the cell also grows and copies it’s sub cellular structures eg mitochondria and ribosomes

Question 11

What happens in the second stage of mitosis?

Answer 11

• mitosis takes place
• One set of chromosomes is pulled to each end of the cell
• the nucleus also divides

Question 12

What happens in the final stage of mitosis?

Answer 12

• in the final stage the cytoplasm and the cell membrane divide
• forming two identical daughter cells

Question 13

What’s the overall summary of mitosis

Answer 13

-mitosis copies one cell into two

Question 14

What are the functions of mitosis?

Answer 14

1. Mitosis is essential for growth and development of multicellular organisms
2. mitosis takes place when a organism repairs itself (eg when a broken bone heals)
3. Mitosis happens during asexual reproduction

Question 15

What is a differentiation?

Answer 15

The process of when cells become specialised

Question 16

What is a stem cell?

Answer 16

A stem cell is an undifferentiated cell which can give rise to more cells of the Same type and differentiate to form other types of cells

Question 17

What are the two types of stem cells?

Answer 17

• Embryonic stem cells

- bone marrow stem cells

Question 18

What is the function of stem cells in embryos?

Answer 18

• Embryonic stem cells can replicate themselves and differentiate into many other cells.
• they can be used to treat conditions like paralysis and diabetes by dividing to replace damaged cells

Question 19

What is the function of stem cells in bone marrow?

Answer 19

• can differentiate into several cell types to replace dead or damaged tissues.
• e.g bone marrow stem cells can form many different types of blood cells.

Question 20

What is the function of meristem cells in plant cells?

Answer 20

Meristem cells can differentiate into any type of plant tissue, at any point in the life of the plant.

Question 21

Where meristem stem cells found?

Answer 21

Roots and buds of a plant

Question 22

What is therapeutic cloning?

Answer 22

• a cloning method where an embryo is produced with the same genetic makeup as the patient
• the stem cells from the embryo will not be rejected by the patient’s immune system

Question 23

What are the advantages of cloning plant s using meristem cells?

Answer 23

• can prevent rare plants from becoming extinct
• can produce large numbers of plants with favourable characteristic.
• can produce identical plants for research

Question 24

What are the issues associated with embryonic stem cells

Answer 24

• embryonic stem cells are sourced from aborted babies/ some people have ethical religious obligations
• development of stem cell therapy is slow expensive and difficult
• adult stem cells infected with viruses could transfer to patients
• if donor stem cells do not have a similar genetic makeup to the patient , immune system could be triggered