Cell Biology

Question 1

Define Osmosis.

Answer 1

The movement of water molecules from a high water concentration to a low water concentration across a selectively permeable membrane.

Question 2

What happens to an animal cell when placed in a solution with a higher water concentration?

Answer 2

It will burst.

Question 3

What happens to a plant cell when placed in a solution with a higher water concentration?

Answer 3

It will become turgid.

Question 4

What happens to an animal cell when placed in a solution with a lower water concentration?

Answer 4

It will shrink.

Question 5

What happens to a plant cell when placed in a solution with a lower water concentration?

Answer 5

It will become plasmolysed.

Question 6

What is passive transport?

Answer 6

When molecules travel down the concentration gradient across a membrane, without using any energy.

Question 7

Give two examples of passive transport.

Answer 7

Osmosis and Diffusion.

Question 8

Name 3 molecules/substances which move by diffusion.

Answer 8

Oxygen, Carbon Dioxide, Glucose.

Question 9

What is active transport?

Answer 9

When molecules are transported against the concentration gradient, requiring the use of chemical energy.

Question 10

Describe the structure of DNA.

Answer 10

Double-stranded helix held by complementary base pairs.

Question 11

Why is the sequence of bases in DNA important?

Answer 11

It codes for the sequence of amino acids in proteins.

Question 12

What are the names of the 4 bases?

Answer 12

Adenine, Cytosine, Guanine and Thymine.

Question 13

Which bases are complimentary to one another?

Answer 13

Adenine - Thymine
Cytosine - Guanine.

Question 14

What is mRNA?

Answer 14

Messenger RNA (mRNA) is a single-stranded copy of the genetic code from DNA that codes for a protein.

Question 15

What are proteins made up of?

Answer 15

Amino acids.

Question 16

What is the role of mRNA?

Answer 16

mRNA carries the genetic code from the nucleus to the ribosome for protein synthesis.

Question 17

Where are proteins synthesised?

Answer 17

The ribosome.

Question 18

What determines the function of proteins?

Answer 18

Their structure is determined by the sequence of amino acids in the protein.

Question 19

What are receptors?

Answer 19

Protein structures on the surface of and within cells that bind to signalling molecules resulting in a chemical response.

Question 20

What are hormones?

Answer 20

Chemical messengers.

Question 21

What are enzymes?

Answer 21

Biological catalysts that speed up the rate of chemical reactions and remain unchanged.

Question 22

What are antibodies?

Answer 22

Y-shaped proteins used in the immune system to fight off infection by binding onto antigens.

Question 23

How does temperature affect enzyme function?

Answer 23

Enzymes are most active at their optimum temperature. If temperature is too low, the reaction will be slow. If the temperature is too high, the enzyme will denature and stop working.

Question 24

How does pH affect enzyme function?

Answer 24

Enzymes are most active at an optimum pH. At extremes of pH, an enzyme may denature and stop working.

Question 25

What is genetic engineering?

Answer 25

When genetic information is transferred from one cell to another cell.

Question 26

In genetic engineering, name the structure which transfers the gene from the human cell to the bacteria.

Answer 26

A plasmid.

Question 27

Name 2 human proteins produced using genetic engineering.

Answer 27

Insulin and human growth hormone.

Question 28

From start to finish, break down the process of genetic engineering.

Answer 28

- Identify the chromosome and section of DNA that contains the required gene. - Extract required gene from chromosome. - Extract plasmid from bacterial cell. - Insert required gene into plasmid. - Insert modified plasmid into host bacterial cell.

Question 29

Name the chemicals which cut the gene from the chromosome and seal the gene into the plasmid in genetic engineering.

Answer 29

Enzymes.