Mitosis and Meiois

Question 1

What is mitosis?

Answer 1

Mitosis is used for growth and repair and produces diploid cells identical to each other and the parent cell.

Question 2

What is meiosis?

Answer 2

Meiosis is used for sexual reproduction and produces haploid cells different to each other and the parent cell.

Question 3

What are the benefits of humans being made of millions of cells?

Answer 3

• Cells can be specialised to do particular tasks
• Groups of cells can function as organs making a more efficient but complex organism
• The organism can grow very large

Question 4

What are normal human body cells called?

Answer 4

Diploids.

Question 5

What happens in mitosis?

Answer 5

In mitosis each chromosome is copied exactly. The new chromosomes are moved to opposite sides of the cell, before the cell divides leaving one complete set of 46 chromosomes in each of the two new cells.

Question 6

How does mitosis help repair damage?

Answer 6

Damaged or old skin cells are replaced by mitosis with identical new skin cells.

Question 7

How does mitosis help growth in plants?

Answer 7

The mass of a plant root increases because of the existing root cells produce more by mitosis.

Question 8

Why is it more efficient for large organisms to be multicellular, rather than single-celled?

Answer 8

It is more efficient for large organisms to be multicellular rather than single-celled because the larger the cell, the smaller the ratio. Small ratio means that they find it difficult to maintain exchange of materials with their environment. Also, with large cells, they could run out of oxygen, and accumulate too much waste, such as carbon dioxide.

Question 9

What is a diploid zygote?

Answer 9

In humans all reproduction is sexual. It involves joining together haploid gamete cells from each parent with half the normal number of chromosomes to make a new cell containing both parents’ genetic material. This is a diploid zygote. (Basically it is the fertilised egg)

Question 10

What are gametes?

Answer 10

The cells from each parent that combine to form the zygote are called gametes. Also, they are cells with half the normal number of chromosomes, and are only used for sexual reproduction

Question 11

What is meiosis responsible for?

Answer 11

Meiosis is responsible for causing genetic variation.

Question 12

What is a zygote?

Answer 12

The cell formed when two gametes combine.

Question 13

What is fertilisation?

Answer 13

The term to describe the joining of two gametes.

Question 14

What is a haploid?

Answer 14

Having half the normal number of chromosomes.

Question 15

What is a diploid?

Answer 15

Having the normal number of chromosomes.

Question 16

What is meiosis sometimes called?

Answer 16

Meiosis is sometimes called reduction division.

Question 17

What happens in meiosis?

Answer 17

• When a parent cell is about to divide, its chromosomes replicate themselves.
• This results in chromosomes with two identical strands called chromatids.
• During meiosis, each chromosome pairs up with its corresponding partner along the centre of the cell.
• The pair of chromosome copies exchange pieces of DNA with one another before the cell divides into two.
• Another division takes place where the chromatids are split in half and each daughter cell receives a different chromosome. This then results in gametes that are haploid and genetically different to one and other.
• During fertilisation, a haploid male gamete (sperm) fuses with a haploid female gamete (egg) forming a diploid zygote.

Question 18

In fertilisation, what part of the egg and sperm join?

Answer 18

Nuclei.