Producing new cells

Question 1

what is cell division used for?

Answer 1

Cell division produces new cells for growth and the repair of damaged tissues and the replacement of dead and damaged cells.

Question 2

What is essential If new cells are required by an organism?

Answer 2

If new cells are required by an organism, the DNA/ chromosomes in the nucleus of a cell must be copied exactly (replicated) so that the new cells are able to grow and work properly.

Question 3

Describe the process of mitosis.

Answer 3

Mitosis is the process by which a nucleus divides into two daughter nuclei, each of which receives exactly the same number of chromosomes as were present in the original nucleus. This is then followed by the division of the cytoplasm to produce two identical daughter cells.

Question 4

What is the first stage of mitosis?

Answer 4

The nucleus containing long uncoiled chromosomes of which each doubles forming two identical chromatids.

Question 5

What is the second stage of mitosis?

Answer 5

Short coiled-up chromosome forms.

made up of two chromatids

Question 6

What is the third stage in mitosis?

Answer 6

Chromosomes get attached at the equator by spindle fibres and are held directly at the centromere.

Question 7

What is the fourth stage of mitosis?

Answer 7

Pair of identical chromatids separate and move to opposite poles. (north pole and south pole).

Question 8

What is the fifth stage of mitosis?

Answer 8

Separated chromatids are now called chromosomes. The cytoplams divides and the nuclear membrane forms

Question 9

What is the final stage of mitosis?

Answer 9

Two identical daughter cells are formed each containing the same number of chromosomes as the original cell. The process can now be repeated.

Question 10

What is chromosome complement?

Answer 10

The characteristic number of chromosomes in an organism’s cell is called its chromosome complement
(count the number of chromosomes present in a cell).

Question 11

what does haploid mean?

Answer 11

A cell with one set of chromosomes is described as haploid.

Question 12

What does diploid mean?

Answer 12

A cell with two sets of chromosomes is described as diploid.

Question 13

Give two examples of sex cells.

Answer 13

sperm and egg cells are sex cells.

Question 14

Why is a sex cell described as haploid?

Answer 14

A sex cell e.g. sperm or egg is described as haploid because it contains one SET of chromosomes.

Question 15

How is a zygote formed?

Answer 15

When two sex cells fuse at fertilisation a zygote is formed.

Question 16

Why is a zygote described as diploid?

Answer 16

Zygote has two SETS of chromosomes so is described as diploid.

Question 17

Are cells produced from the zygote, by mitosis diploid or haploid?

Answer 17

All cells produced from a zygote are also diploid which means they contain two sets of chromosomes. The chromosomes in a zygote can be arranged in matching pairs.

Question 18

What happens to the zygote after fertilisation?

Answer 18

After fertilisation the zygote continues to divide by mitosis.

Question 19

What does the specialisation of cells lead to?

Answer 19

The specialisation of cells leads to the formation of a variety of cells, tissues and organs.

Question 20

What are tissues?

Answer 20

Cells performing the same job link together as tissues.

Question 21

What is an organ?

Answer 21

An organ is a structure composed of several different tissues coordinated to perform one or more functions. E.g. heart muscle tissue, blood vessel tissue and nerve tissue make up the organ called a heart.

Question 22

Name the stages of the hierarchy of organisation within a multicellular organism.

Answer 22

1. Specialised cell- e.g muscle cell
2. Tissue- muscle tissue
3. Organ-heart
4. System-circulatory system
5. Organism-circulatory system makes up part of the human body.

Question 23

What is a multicellular organism made up of?

Answer 23

A multicellular organism is made up of several systems working together for survival of the organism.

Question 24

What are the two cell types in blood tissue?

Answer 24

Red blood cell and white blood cell.

Question 25

What are the specialised structural features of a red blood cell?

Answer 25

small size and biconcave shape present a relatively large surface area; rich supply of haemoglobin present.

Question 26

What is the function of red blood cells?

Answer 26

Uptake and transport of oxygen to living cells.

Question 27

What are the specialised structural features of a white blood cell?

Answer 27

Able to change shape; sacs of microbe-digesting enzymes present in some types.

Question 28

What is the function of white blood cells?

Answer 28

Destruction of invading microbes.

Question 29

What is the cell type of the nerve tissue called?

Answer 29

Motor neuron.

Question 30

What are the specialised structural features of a motor neuron cell?

Answer 30

Axon (long insulated extension of the cytoplasm).

Question 31

What is the function of the motor neuron cell?

Answer 31

Transmission of nerve impulses.

Question 32

What are the specialised structural features and functions of a sperm cell?

Answer 32

Has a tail to help to help it swim through the female reproductive system to the egg.

Question 33

What are the cell types of the tissue mesophyll?

Answer 33

Palisade mesophyll and spongy mesophyll.

Question 34

What are the specialised structural features in a palisade mesophyll?

Answer 34

Chloroplasts present; columnar shape (allows densely packed green layer to be presented to light).

Question 35

What is the function of the palisade mesophyll cell?

Answer 35

Primary region of light absorption and photosynthesis.

Question 36

What are the specialised structural features in a spongy mesophyll cell?

Answer 36

“round” shape allows loose arrangement in contact with the moist air spaces for absorption of carbon dioxide.

Question 37

What is the cell type of Xylem tissue called?

Answer 37

Vessel cell.

Question 38

What are the specialised structural features of a vessel cell?

Answer 38

Hollow tube; wall strengthened by lignin; lignin deposited as rings or spirals allowing expansion and contraction.

Question 39

What is the function of the vessel cell?

Answer 39

Support and water transport up the plant.

Question 40

What are the cell types of phloem tissue?

Answer 40

Sieve tube and companion cell

Question 41

What are the specialised structural features of sieve tube cells?

Answer 41

Sieve plates and continuous stream of cytoplasmic strands (but no nucleus).

Question 42

What is the function of a sieve tube?

Answer 42

Transport of soluble carbohydrates up and down the plant.

Question 43

What are the specialised structural features of a companion cell?

Answer 43

Large nucleus in relation to cell size.

Question 44

What is the function of a companion cell?

Answer 44

Control of sieve tube functions.

Question 45

What are stem cells?

Answer 45

Stem cells are unspecialised animal cells involved in tissue growth and repair.

Question 46

What are the functions of stem cells?

Answer 46

They can divide (by mitosis) in order to self-renew, (and remain unspecialised).

Have the potential to become different types of cells when required e.g. to replace cells that have died, become damaged or lost.

Question 47

Name two types of stem cells.

Answer 47

Embryonic stem cells and tissue stem cells.

Question 48

Where do embryonic stem cells come from?

Answer 48

embryonic stem cells can be obtained from the embryo at a very early stage.

Question 49

Where do tissue stem cells come from?

Answer 49

Tissue stem cells can be found in the body throughout life.

Question 50

What type of cells do embryonic stem cells have the potential to become?

Answer 50

These cells have the potential to become any type of cells found in the body. For example, an embryonic stem cell could have become a nerve cell, skin cell, bone cell, etc.

Question 51

What type of cells do tissue stem cells have the potential to become?

Answer 51

These cells have the potential to become only a few types of cells. For example, adult stem cells in bone marrow (inside your thigh bone) can only become types of white blood cells, red blood cells but no other type of cell.