B2 - Cell division

Question 1

Differentiation in plants vs animals

Answer 1

• Most types of animal cell differentiate at an early stage.
• Many types of plant cells retain the ability to differentiate throughout life.

Question 2

What is differentiation

Answer 2

A cell acquires different subcellular structures to enable it to carry out a certain function.
It has become a specialised cell.

Question 3

What is cell division used for in grown animals

Answer 3

Repair and replacement of cells

Question 4

How many chromosomes + pairs do we have

Answer 4

46 chromosomes - 23 pairs

Question 5

Smallest to largest structures in the nucleus

Answer 5

1. Allele - form of a gene (recessive or dominant)
2. Gene - a length of DNA coding for 1 protein
3. DNA
4. Chromosome
5. Nucleus

Question 6

What happens in the cell cycle

Answer 6

1. Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria.
2. The DNA replicates to form two copies of each chromosome.
   2 (mitosis). One set of chromosomes is pulled to each end of the cell and the nucleus divides.
3. Finally the cytoplasm and cell membranes divide to form two identical cells.

Question 7

What are stem cells

Answer 7

Undifferentiated cells that can produce specialised cells and more stem cells

Question 8

Stem cells in humans

Answer 8

Stem cells from human embryos can be cloned and made to differentiate into most different types of human cells.

Stem cells from adult bone marrow can form many types of cells including blood cells.

Question 9

Stem cells in plants

Answer 9

Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant.

Question 10

What conditions could stem cells help with

Answer 10

diabetes and paralysis

Question 11

What is therapeutic cloning

Answer 11

An embryo is produced with the same genes as the patient.
Stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment

Question 12

Stem cell use risks

Answer 12

Transfer of viral infection
Ethical or religious objections

Question 13

What can plant stem cells be used for

Answer 13

Produce clones of plants quickly and economically.
Rare species can be cloned to protect from extinction.
Crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers.