Topic 1 - Cell Biology

Question 1

How are sperm cells specialised?

Answer 1

A tail to swim, half a set of DNA, lots of mitochondria for energy, the acrosome in the head contains enzymes so that it can pierce the egg

Question 2

How are nerve cells specialised?

Answer 2

Insulated myelin sheath to send messages faster, dendrites to connect to other nerve cells

Question 3

How are root hair cells specialised?

Answer 3

Large surface area, lots of Mitochondria for Active Transport

Question 4

When do animal cells differentiate?

Answer 4

At an early stage

Question 5

When can plant cells differentiate?

Answer 5

Many plant cells can differentiate throughout their life

Question 6

Where are plant stem cells (meristem) located?

Answer 6

At the tips and the roots

Question 7

How many pairs of chromosomes are in a typical body cell?

Answer 7

23 pairs (46 chromosomes)

Question 8

What cells does mitosis make?

Answer 8

Normal body cells for growth and repair

Question 9

Are the products of mitosis identical?

Answer 9

Yes

Question 10

What is a stem cell?

Answer 10

An undifferentiated cell

Question 11

List the stages of the cell cycle

Answer 11

Rest phase, DNA replicates, chromosomes arrange themselves along the centre of the nucleus, half of each chromosome moves to one side of the nucleus, nucleus divides, cell divides, back to rest phase…

Question 12

What are the two types of animal stem cells?

Answer 12

Embryonic and adult stem cells

Question 13

What can stem cells help with?

Answer 13

Diabetes and paralysis

Question 14

List the stages of therapeutic cloning

Answer 14

Problem identified
Skin cell removed from patient
Nucleus of skin cell is inserted into empty egg cell
Egg is given electric shock
Mitosis starts
Embryo grows
Stem cells are removed from the embryo
Stem cells are forced to specialise
New cells used for treatment

Question 15

What is an advantage of therapeutic cloning?

Answer 15

Stem cells are not rejected

Question 16

Why can embryonic stem cells be a disadvantage?

Answer 16

Ethical reasons
Rapid division more likely to result in cancerous cells

Question 17

Why is meristem useful?

Answer 17

Rare species can be cloned
Crops can be bred to be disease resistant

Question 18

Definition of diffusion

Answer 18

The net movement of particles from an area of high concentration to an area of low concentration until equilibrium is reached

Question 19

Factors which affect diffusion

Answer 19

Concentration gradient, temperature, surface area

Question 20

Osmosis definition

Answer 20

The movement of water particles from an area of high concentration to an area of low concentration across a partially permeable membrane

Question 21

Active Transport definition

Answer 21

The net movement of particles from an area of low concentration to an area of high concentration against the concentration gradient, across a partially permeable membrane (requires energy)

Question 22

Are Bacteria Cells eukaryotic or prokaryotic?

Answer 22

Prokaryotic

Question 23

How is the xylem specialised?

Answer 23

There are no top and bottom walls between xylem vessels, so there is a column of
water running through them. Their walls
become thickened and woody. They therefore support the plant.

Question 24

Give examples of substances which have an increased surface area

Answer 24

Villi, alveoli, gills, roots