B5:Growth and Development

Question 1

How many different bases does DNA have?

Answer 1

4 - Adenine, Thymine, Guanine, Cytosine

Question 2

Which bases always pair together?

Answer 2

A & T

G & C

Question 3

DEFINE: Gene

Answer 3

A gene is a section of DNA that contains the instructions for one particular protein

Question 4

What are proteins made of?

Answer 4

Proteins are chains of amino acids joined together

Question 5

Describe how the order of the bases determine what protein is made

Answer 5

Cells make proteins by joining amino acids together in a particular order. The order of the bases tells the cell what order to put the amino acids together. Each set of three bases (triplet code) codes for one amino acid. There is also a start and end code.

Question 6

Where in the cell are genes found?

Answer 6

DNA is found in the nucleus

Question 7

Where in the cell are proteins made?

Answer 7

They are made in cell organelles called ribosomes.

Question 8

What is messenger RNA (mRNA) ?

Answer 8

mRNA is very similar to DNA but it is shorter and only one strand. It is a messenger molecule that copies DNA from the nucleus and takes it to the ribosome for proteins to be made

Question 9

During cell growth does the number of chromosomes double or halve?

Answer 9

Doubles - MITOSIS

Question 10

Give differences between Mitosis & Meiosis

Answer 10

Meiosis produces gametes (they have half the number of chromosomes) and involves two divisions. Mitosis produces genetically identical cells and purpose is to provide new cells for growth and repair.

Question 11

What is the name of the cell when two gametes combine?

Answer 11

Zygote

Question 12

In a human embryo, all the cells are undifferentiated until what stage?

Answer 12

Cells are undifferentiated until the eight cell stage

Question 13

How are stem cells in a embryo different from adult stem cells?

Answer 13

Adult stem cells are partially specialised. They arent as versatile as embryonic stem cells, they can only differentiate into certain types of cell

Question 14

What determines the type of cell a stem cell becomes?

Answer 14

The type of cell a stem cell develops into depends on the genes that are active. Stem cells in embryos can switch on any gene.

Question 15

Describe how cloning could be used to make embryonic stem cells.

Answer 15

You can take a egg cell and remove its genetic material, a nucleus of a body cell you cloning can be inserted into the ‘empty’ egg cell. Under the right conditions inactive genes of the body cell can be reactivated so that an embryo forms. Embryonic stem cells can then be extracted and controlled to form any type of specialised cell

Question 16

What name is given to the parts of the plants where mitotically active cells are found?

Answer 16

In plant tissues called meristems

Question 17

Name two types of tissue that the unspecialised cells in plants can turn into.

Answer 17

Tissues - xylem or phloem

These tissues can group together to form organs like leaves, roots, stems and flowers.

Question 18

DEFINE: cutting

Answer 18

A cutting is a part of a plant that has been cut off it

Question 19

What do cuttings grow into?

Answer 19

Its will grow into a whole new clone plant to the ‘parent’ plant

Question 20

Why are cuttings useful?

Answer 20

They are useful becaus eyou can take cuttings from plants with desirable characteristics. Then plant them to produce genetically identical copies of the parent plant.

Question 21

What can be added to soil to encouarge cuttings to grow roots?

Answer 21

Rooting powder contains plant hormones ‘auxins’. Theyll produce roots rapidly