5.1 and 5.2 Cell Division/in Sexual Reproduction

Question 1

What is mitosis?

Answer 1

Cell division that produces identical new cells from the original cell

Question 2

Explain the process of mitosis

Answer 2

1. All of the organelles in a cell replicate
2. All of the DNA replicates
3. All of the enzymes needed for cell division are produced by the cell
4. Prophase, metaphase, anaphase and telophase

Question 3

What do chromosomes contain?

Answer 3

Alleles in the genes which must be passed on to each new cell

Question 4

What are the names of unspecialised cells in plant and animal embryos?

Answer 4

Stem cells

Question 5

What is cell division mostly for in animals?

Answer 5

Replacement and repair, because most animal cells differentiate early in development

Question 6

What is cell division mostly for in plants?

Answer 6

Growth, because plant cells can differentiate throughout the life of the plant

Question 7

What are cells of offspring made by asexual reproduction produced by?

Answer 7

Mitosis, so they contain the same alleles as their parents

Question 8

Which type of cell division produces two identical cells from the original cell?

Answer 8

Mitosis

Question 9

How to remember mitosis?…

Answer 9

MITosis = Making Identical Two

Question 10

Name the 4 stages in the mitosis checkpoint stage of the mitosis cycle

Answer 10

• prophase
• metaphase
• anaphase
• telophase

PMAT

Question 11

What happens in the prophase stage?

Answer 11

The chromosomes condense, the centrioles move to opposite poles, the spindle apparatus spreads (ready to force apart) and the nuclear membrane dissolves

Question 12

What happens in the metaphase stage?

Answer 12

All chromosomes are aligned to the equator of each cell

Question 13

What happens in the anaphase stage?

Answer 13

The proteins that hold the sister chromatids together degrade so all of the chromosomes are pulled to each pole

Question 14

What happens in the telophase stage?

Answer 14

Once the chromosomes are separated, the cell splits into 2 separate cells

Question 15

Which process splits the cells in two in mitosis?

Answer 15

Cytokinesis

Question 16

What are sister chromotids?

Answer 16

Individual chromosomes that make a pair of chromosomes

Question 17

Explain the stages of meiosis

Answer 17

1. Replicate the pairs of chromosomes in a cell
2. The cells split similarly to mitosis, with a set of each pair of chromosomes, called a diploid
3. The cells split again without replicating the chromosomes so each cell only has one pair of chromosomes, called a haploid

Question 18

How do cells in reproductive organs divide?

Answer 18

Meiosis, to form gametes

Question 19

What are the gametes in humans?

Answer 19

Sperm and ova

Question 20

Why does sexual reproduction lead to variation?

Answer 20

The different chromosomes from each parents fuse so half the genetic info comes from father, other half from mother

Question 21

When the gametes join at fertilisation which process carries on with developing the embryo?

Answer 21

Mitosis splits the cells

Question 22

How to remember meiosis?…

Answer 22

MEiosis = Making Eggs

Question 23

What is cell division necessary for?

Answer 23

The growth of an organism and the repair of damaged tissue

Question 24

Why does uncontrolled mitosis lead to the formation of tumours?

Answer 24

As the cells divide uncontrollably, tumours form

Question 25

Normal cells usually die after going through mitosis around 50 times (depending on the type of cell) but cancer cells are often immortal. Why can this be a problem?

Answer 25

The cancer cells can spread around the body and take away resources from the organs, eventually causing the organs to stop working

Question 26

Explain why a malignant tumour is more dangerous than a benign tumour

Answer 26

The malignant tumours have their own blood supply

Question 27

Name the 3 types of treatment for cancer

Answer 27

• removal of tumour by surgery
• chemotherapy
• radiotherapy

Question 28

Which 2 treatments of cancer are more suited for targeting tumours in one specific area and why?

Answer 28

• radiotherapy, because you only aim the X-rays at one area of the body
• removal of tumours by surgery because they will only operate on the targeted area

Question 29

Which treatment is necessary for cancer that has spread around the body?

Answer 29

Chemotherapy because it is a drug in your bloodstream that travels the body and kills the cancerous cells

Question 30

Why can’t chemotherapy be used on pregnant women?

Answer 30

Chemotherapy relies on a drug that travels in your bloodstream and kills cells that are dividing, and the cells of the embryo in the uterus are dividing