Biology Y09 Aut1

Question 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

Why do we use iodine to stain the cells?

Answer 2

to help us see the sub cellular structures of the cell

Question 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

What is a micrometer?

Answer 4

1/1000th of a millimeter

Question 5

What is the equation used in microscopy?

Answer 5

magnification = image size/actual size

Question 6

What are stem cells?

Answer 6

undifferentiated cells

Question 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

Where are stem cells found in plants?

Answer 8

meristem - tips of roots and tips of shoots

Question 9

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

Answer 9

In humans, they can used to treat diseases such as leukaemia and therapeutic cloning. In plants, they can be used to grow lots of crop plants quickly.

Question 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

Describe the risks of using stem cells in humans.

Answer 11

passing on viral diseases plus the ethical issues of using embryos

Question 12

What causes tumours?

Answer 12

uncontrolled cell division

Question 13

What is a benign tumour?

Answer 13

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

Question 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

How is cancer spread through the body?

Answer 15

through the bloodstream

Question 16

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

Answer 16

genes and lifestyle

Question 17

Why do multicellular organisms need specialised exchange organs?

Answer 17

They have small SA:V so need organs to bring substances from outside to the internal cells.

Question 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

How do you calculate percentage change in mass?

Answer 19

change in mass/starting mass x 100

Question 20

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

Answer 20

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