2(a, b, c)

Question 1

Function of nucleus?(2)

Answer 1

Contains the DNA of a cell, much of which serves as protein-coding genes.
Surrounded by its own membrane.

Question 2

Function of cytoplasm?

Answer 2

Where chemical processes (controlled by enzymes) take place.

Question 3

Function of cell membrane?

Answer 3

Controls what goes in and out of the cell.

Question 4

Function of mitochondrion?

Answer 4

Site of aerobic respiration.

Question 5

Function of chloroplast?

Answer 5

Location of photosynthesis. Contains the photopigment chlorophyll.

Question 6

Function of vacuole?

Answer 6

Contains water, mineral ions, proteins, pigments and other molecules. This collection is called cell sap.

Question 7

Define Organelle.

Answer 7

A specialised structure within a cell; nucleus, vacuole, chloroplast.

Question 8

Define Cell.

Answer 8

The smallest structural unit of an organism capable of independent functioning; sperm cell, red blood cell, root hair cell.

Question 9

Define Tissue.

Answer 9

Collection of cells performing a similar function; muscle tissue, blood.

Question 10

Define Organ.

Answer 10

Collection of tissues performing similar function; heart, skin, leaf.

Question 11

Function of ribosomes?

Answer 11

Proteins are assembled from amino acids by molecular structures called ribosomes. Cells contain thousands of these but they are too small to be seen under a microscope.

Question 12

Function of cytoskeleton?

Answer 12

Cytoskeleton is a network of protein fibres running through the cell. They provide strength to the structure of the cell and give routes for organelles to be moved around the cell.

Question 13

Function of cellulose and glycogen?(2)

Answer 13

Cellulose is used to make the cell wall of plants.
Glycogen is a store of glucose molecules in animals cells can be broken down to glucose.

Question 14

Function of proteins and lipids?(2)

Answer 14

Proteins used to make enzymes, cytoskeleton and transport some molecules and ions across cell membrane.
Lipids are a component of cell membranes and an energy store.

Question 15

How many naturally occurring Amino Acids are there?

Answer 15

20.

Question 16

Lipids have which elements in?

Answer 16

Carbon, Hydrogen, Oxygen.

Question 17

DNA has which elements in?

Answer 17

Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous.

Question 18

Describe the structure of protein and structure of a triglyceride(lipid)?(2)

Answer 18

Four Amino Acids in a protein.
Three fatty acids and glycerol make up triglyceride.

Question 19

State the composition of starch in plants, and glycogen in animals.

Answer 19

Four sugars.

Question 20

Adenine pairs with _ and Cytosine pairs with _

Answer 20

Thymine. Guanine.

Question 21

What is the typical number of base pairs in a human gene?

Answer 21

12,000.

Question 22

Test for starch?

Answer 22

Iodine solution. Positive: blue/black. Negative: yellow.

Question 23

Test for glucose?

Answer 23

Benedict solution while also heating up to above 80 celsius. Positive: brick red. Negative: blue.

Question 24

Test for protein?

Answer 24

Biuret 1 and Biuret 2. Positive: purple. Negative: blue.

Question 25

Test for lipid?

Answer 25

Use ethanol to dissolve lipid, then mix with water. Positive: cloudy. Negative: clear.

Question 26

What is an enzyme?(3)

Answer 26

Enzymes are biological catalysts that speed up the rate of a reaction in the body because it is at too low a temperature(37*C). Everything a cell does depends on which enzymes it can make.
The molecule that an enzyme acts on is called its substrate, each enzyme has a small area on its surface called the active site. When a substrate joins up with the active site it lowers the energy needed for the ruction to start.
The active site has a 3D shape that is complimentary to the substrate, this is called the lock and key model.

Question 27

Define Enzyme optimum temperature and Enzyme optimum pH.

Answer 27

The temperature that supports the maximum rate of an enzyme controlled reaction.
The pH that supports the maximum rate of an enzyme controlled reaction.

Question 28

Define Enzyme optimum temperature and how temperatures effects can be investigated on activity of Amylase.(5)

Answer 28

The digestive enzyme amylase breaks down starch into sugar, therefore the speed at which the starch disappears is the measure of the activity of the amylase.
Spots of iodine solution are placed on the dips of a spotting tile. Then, 5ml of starch suspension is added to 5ml of amylase solution and immediately a pipette is used to take a sample and added to one spotting tile.
Samples are then taken every 30 seconds for 10 minutes, and on the spotting tile a gradual colour change from blue to yellow should be seen as less and less starch is present in the solution.
Upon reaching the first sample that remains yellow, record the time. Repeat the experiment for temperatures between 20 and 50 Celsius.

Question 29

How can pH effects can be investigated on activity of Catalase?(5)

Answer 29

Buffer solutions are solutions of salts that resist changes in pH, these can be prepared for keeping different values of pH hence are useful for finding the effect of pH on enzyme activity.
Hydrogen peroxide(product of metabolism, toxic) is broken down in cells by catalase into water and oxygen. Potato cells contain lots of catalase.
5ml of blended potato(to release catalase) is placed in a boiling tube with 5ml of pH(5-8) solution and then after shaking, left for a few minutes.
Then 5ml of hydrogen peroxide solution is added to the mixture and a bung with a delivery tube is quickly inserted into the boiling tube.
At the end of the delivery tube a beaker of water is placed, and the rate of the reaction is measured in bubbles(of oxygen) per minute.

Question 30

Carbohydrates have which elements in?

Answer 30

Carbon, hydrogen, oxygen.

Question 31

Proteins have which elements in?

Answer 31

Carbon, Nitrogen, hydrogen and Oxygen.

Question 32

What are the two types of stem cell?(4)

Answer 32

Embryonic stem cell, found in the early stage of development of the embryo.
Can differentiate into any type of cell.
Adult stem cell, found in certain adult tissues such as bone marrow, skin, and lining of intestine.
Can not differentiate into any type of cell but can form a number of specialised tissues. For example, bone marrow cells can divide many times but are only able to produce different types of red and white blood cells.

Question 33

What is stem cell therapy?(2)

Answer 33

The use of stem cells to treat a disease, or to repair damaged tissues. This is most common with bone marrow transplants.
Bone marrow transplants are used to treat patients with leukaemia, replacing cells that were destroyed from chemotherapy.

Question 34

What are the advantages and disadvantages of using stem cells in medicine?(2)

Answer 34

Scientists through isolating and culturing embryonic stem cells might in the future be used to treat many diseases.
However, many people morally object to using stem cells from human embryos.