Biology Y09 Autumn

Question 1

1 Explain why a specimen on a microscope slide should be one cell thick.

Answer 1

This ensures light is able to pass through the specimen, so we can see inside it.

Question 2

2 Why do we use iodine to stain the cells?

Answer 2

To help us see the sub cellular structures of the cell.

Question 3

3 Describe the process of making an onion cell slide.

Answer 3

Place a thin sample on a slide. Add a drop of iodine. Carefully add cover slip to avoid bubbles.

Question 4

4 What is a micrometer?

Answer 4

1/1000th of a millimetre.

Question 5

5 What is the equation used in microscopy?

Answer 5

Magnification= image size/actual size.

Question 6

6 What are stem cells?

Answer 6

Undifferentiated cells.

Question 7

7 What is the difference between adult and embryonic stem cells?

Answer 7

Adult stem cells can only become certain types of cell, embryonic stem cells can become any type of cell.

Question 8

8 Where are stem cells found in plants?

Answer 8

Meristem- tips of roots and tips of shoots.

Question 9

9 Describe two uses of stem cells in humans and two uses of stem cells in plants.

Answer 9

In humans they are used to treat diseases such as leukaemia and therapeutic cloning. In plants they are used to grow lots of crop plants quickly and economically that are disease resistant.

Question 10

10 What is therapeutic cloning?

Answer 10

Taking the nucleus of a body cell of someone with a disease and placing it into an empty egg cell to create an embryo, stem cells from which can be used to treat the original person.

Question 11

11 Describe the risks of using stem cells in humans.

Answer 11

Passing on viral diseases, ethical issues of using embryos.

Question 12

12 What causes tumours?

Answer 12

Uncontrolled cell division.

Question 13

13 What is a benign tumour?

Answer 13

Abnormal growth of cells contained in one area which do not invade neighbouring tissues.

Question 14

14 What is a malignant tumour?

Answer 14

Cancerous growths which invade neighbouring tissues and can spread to other parts of the body to form secondary tumours.

Question 15

15 How is cancer spread through the body?

Answer 15

Through the bloodstream.

Question 16

16 Give 2 things that can increase the chance of developing cancer.

Answer 16

Genes, lifestyle.

Question 17

17 Why do multicellular organisms need specialised exchange organs?

Answer 17

They have small Surface area: volume so need organs to bring substances from outside to the internal cells.

Question 18

18 Describe three common features of lungs, gills and the small intestine.

Answer 18

Large surface area, lots of blood vessels and thin membranes..

Question 19

19 How do you calculate percentage change in mass?

Answer 19

Change in mass/starting mass x 100

Question 20

20 How would you use a graph to find the concentration of solutes in the plant tissue?

Answer 20

Where the line on the graph crosses the x axis. This indicates no change in mass.