B5

Question 1

Cells divide by two processes which are?

Answer 1

Mitosis and Meiosis

Question 2

What do similar cells form?

Answer 2

Tissue

Question 3

What do groups of tissues form?

Answer 3

Organ

Question 4

What do groups of organs do?

Answer 4

Make up systems within the whole organism

Question 5

List three reasons why Mitosis occurs?

Answer 5

For growth, repair and to replace old tissues

Question 6

After Mitosis occurs, what does each new cell have?

Answer 6

Identical sets of chromosomes as the parent cell and the same number of chromosomes as the parent cell and the same genes as the parent cell

Question 7

To enable Mitosis to take place, what do cells have to go through?

Answer 7

A cycle of growth and then division

Question 8

What happens when the cell enters the growth phase of the cycle during Mitosis?

Answer 8

The number of organelles increase and the chromosomes are copied - the two strands of each DNA molecule separate and new strands form alongside

Question 9

What two places does Meiosis only take place in?

Answer 9

Testes and ovaries

Question 10

What does Meiosis produce?

Answer 10

Gametes for sexual reproduction

Question 11

How many chromosomes do gametes contain?

Answer 11

Half the number of chromosomes as the parent cell

Question 12

What happens during fertilisation?

Answer 12

A male gamete and a female gamete fuse together to produce a single boy cell, called a zygote

Question 13

How many chromosomes does the zygote have?

Answer 13

One whole set of chromosomes because gametes only contain half the number of parent cells, so when both form together it creates a full set

Question 14

In each new chromosome, how many chromosome come from each parent?

Answer 14

One chromosome from the father and one chromosome from the mother

Question 15

When the zygote divides, what does it produce?

Answer 15

A cluster of cells called an embryo

Question 16

Genes are present in the chromosomes in each cell nucleus. What do the genes control?

Answer 16

Growth and development in organisms and the development of characteristics

Question 17

How do genes control characteristics?

Answer 17

By providing instructions for the production of proteins

Question 18

The instructions used to help create characteristics are in the form of a code which is made up of four bases. These bases always pair up in what way?

Answer 18

Adenine (A) pairs with thymine (TY) and cytosine (C) pairs with guanine (G)

Question 19

DNA is too large to leave the nucleus meaning it has to stay inside. The production of proteins takes place outside the nucleus in the cytoplasm. How does this work?

Answer 19

Information stored in the genes has to be transferred into the cytoplasm

Question 20

How is information in the genes transferred to the cytoplasm?

Answer 20

1- The relevant section of DNA is unzipped
2- Instructions are copied onto smaller molecules called mRNA
3- These molecules leave the nucleus and carry instructions to the ribosomes
4- The ribosomes follow the instructions to make the relevant protein

Question 21

A group of three base pairs codes for one amino acid in a protein chain, called what?

Answer 21

A triplet code

Question 22

The structure of the protein depends on what?

Answer 22

The amino acids which make it up

Question 23

Up to the eight cell stage, all cells in a human embryo…?

Answer 23

Are unspecialised

Can have any gene switched on to form any kind of specialised cell

Question 24

After the eight cell stage, the cells in an embryo…?

Answer 24

Become specialised

Form different types of tissue

Question 25

Stem cells could potentially be used to...?

Answer 25

Help treat diseases and disorders | Repair damage to various tissues

Question 26

What are the three sources of stem cells?

Answer 26

1- Embryos 2- Blood from the umbilical chord 3- Adult stem cells from bone marrow

Question 27

What process do plant cells divide by?

Answer 27

Mitosis

Question 28

New cells in plants specialise into the cells of...?

Answer 28

Roots Leaves Flowers

Question 29

Which area of the plant does plant growth occur in?

Answer 29

Meristems - sites where unspecialised cells are dividing by mitosis

Question 30

What are the two types of meristem?

Answer 30

Lateral, which leads to increased girth | Apical, which leads to increased height in longer roots

Question 31

If the hormonal conditions in their environment are changed, the unspecialised plant cells can develop into other...?

Answer 31

Tissues - e.g xylem and phloem | Organs - e.g leaves, roots and flowers

Question 32

Xylem tubes are used by the plant to...?

Answer 32

Transport water and soluble mineral salts from the roots to the stem and leaves Replace water lost during transpiration and photosynthesis

Question 33

What are phloem tubes used by the plant for?

Answer 33

To transport dissolved food to the whole pant for respiration or storage

Question 34

What is one way plants can be reproduced?

Answer 34

1 - Cuttings are taken from the plant 2 - The cuttings are put into a rooting hormone 3 - Roots start to form and the new plants develop

Question 35

When plants respond to light, they change direction in which they grow. What is this called?

Answer 35

Phototropism