1.2 Cell division

Question 1

1.2.1 Chromosomes

Chromosomes

what is it made of, where is it found, number of chromosomes in body

Answer 1

Found in the nucleus
made of DNA molecules
each chromosome carries 23 genes
altogether, a human has 46 chromosomes (23 pairs)

Question 2

1.2.2 Mitosis and cell cycle

Stages of mitosis/cell cycle

Answer 2

During the cell cycle the genetic material is doubled and then divided into two identical cells.

1. Before cell division, sub-cellular structures are duplicated. DNA replicates to form two copies of each chromosome.
2. In 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 3

1.2.2 Mitosis and cell cycle

Stage names for the cell cycle

with explaination

Answer 3

1. Interphase/cell growth: chromosomes double, subcellular structures increase
2. Mitosis: chromosomes line up and are pulled to either side of the cell
3. Cytokinesis: two identical daughter cells are formed, when cytoplasm and cell membrane divide.

Question 4

1.2.3 Stem cells

What is stem cells

Answer 4

an undifferentiated cell of an organism which is capable of diving many more cells of the same type, creating other type of cells in the body (using differentiation)

Question 5

1.2.3 Stem cells

Function of stem cells in embryos

Answer 5

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

Question 6

1.2.3 Stem cells

Function of stem cells in adults

Answer 6

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

Question 7

1.2.3 Stem cells

Function of stem cells in meristems

meristem plants

Answer 7

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

Stem cells from meristems in plants can be used to 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.

source: tip of roots/shoots

Question 8

1.2.3 Stem cells

What can stem cells treat?

Answer 8

Can help conditions like diabetes and paralysis

Question 9

1.2.3 Stem cells

What happens in therapeutic cloning?

Answer 9

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.

stem cells of embryo is used

Question 10

1.2.3 Stem cells

Benefits of using stem cells

Answer 10

• great potential to treat a wide variety of diseases from diabetes and paralysis
• organs developed from a patient’s own stem cells reduces risk of organ rejection & the need to wait for donation
• adult stem cells are already successfully used

Question 11

1.2.3 Stem cells

Risk of using stem cells

Answer 11

• Stem cells made in lab could be infected with a virus that can be spreaded to patient
• risk of stem cells made in labs being mutated, that can lead to development of cancer cells
• low number of stem cell donors

Question 12

1.2.3 Stem cells

Social issues of stem cells

Answer 12

• Possible for embryonic stem cells to be collected before birth/after birth and stored however, can be expensive and** isn’t an option for everyone**
• a** lack of peer-reviewed clinical evidence** of the success of stem cell treatment
• educating public of what stem cells can be used/not used for.

Question 13

1.2.3 Stem cells

Ethical issues of stem cells

Answer 13

• May be sourced from unused embryos produced in IVF treatment however who gives permission?
• is it right to create embryos through therapeutic cloning, and destroy them?
• should an embryo be treated as a person with human rights?