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Question 1

How can stem cells in plants be used to clone them?

Answer 1

1. In plants, stem cells are found in the meristems
2. Throughout the plants entire life, cells in the meristematic tissue can differentiate into any type of cell
3. These stem cells can be used to produce clones of whole plants quickly and cheaply
4. They can be used to grow more plants of rare species
5. They are also used to grow crops of identical plants that have desired features for farmers

Question 2

What is therapeutic cloning?

Answer 2

1. An embryo can be made from the same genetic information as the patient
2. This means that the stem cells produced from it would also contain the same genes and so wouldnt be rejected by the patients body if used to replace faulty cells

Question 3

How are stem cells used to cure diseases?

Answer 3

1. Medicine already uses adult stem cells to cure disease. E.g., stem cells are transferred from the bone marrow of a healthy person can replace faulty blood cells
2. Embryonic stem cells can be used to replace faulty cells in sick people - you could make insulin-producing cells for people with diabeties, nerve cells for people paralysied by spinal injuries

Question 4

How to culture bacteria in the lab?

Answer 4

1. Sterilise petri dish and agar using an autoclave to kill any microorganisms
2. Sterilise inoculating loop by heating it in a Bunsen flame until red hot, then let it cool to kill microbes
3. Dip loop in bacterial culture and streak across agar in a zigzag pattern
4. Replace lid quickly to prevent contamination from the air
5. Seal the dish with adhesive tape, not all the way around, to prevent microorganisms from the air from contaminating the culture and to stop microbes from getting out
6. Store dish upside down to stop condensation dripping onto the agar
7. Incubate at 25°C to reduce the risk of growing harmful pathogens

Question 5

What is a benign tumour?

Answer 5

1. Benign tumours are growths of abnormal cells contained in one place, usually within a membrane
2. They do not invade other parts of the body
3. It is non-cancerous
4. It can still be harmful if it grows large enough to put pressure on organs
5. E.g benign tumours on the brain can be very dangerous because there is no extra space for them to grow into

Question 6

What is a malignant tumour?

Answer 6

1. A malignant tumour is a cancerous tumour that grows very quickly and spreads in the body
2. They invade neighbouring healthy tissues
3. The initial tumour may break up, releasing small clumps of cells into the bloodstream or lymphatic system
4. They are carried around the body and may causes a secondary tumour on another organ

Question 7

How does tar in tobacco smoke affect the lungs?

Answer 7

1. Turns the lungs from pink to grey
2. Makes smokers much more likely to develop bronchitis
3. Can lead to a breakdown in the structure of alveoli, causing chronic obstructive pulmonary disease (COPD)
4. Tar is a carcinogen, it increases the risk of lung cancer

Question 8

How does chemicals in tobacco smoke affect the trachea and bronchi?

Answer 8

1. The cillia in the trachea and bronchi that move mucus, bacteria and dirt away from the lungs are anaesthetised by some of the chemicals in tobacco smoke
2. This means they stop working for a time, allowing dirt and pathogens down the lungs increasing the risk of infection

Question 9

How does alcohol cause brain and liver damage?

Answer 9

1. May develop cirrhosis of the liver - disease that desatroyes liver tissue - liver cells replaces with scar tissue that cannot carry out vital functions
2. Is a carcinogen - Increased risk of liver cancer
3. Long term heavy alcohol damages the brain - can no longer function properly

Question 9

How does smoking affect the heart?

Answer 9

1. Smoking narrows the blood vessels in your skin, ageing it
2. Nicotine makes the heart-rate increase while other chemicals damage the lining of arteries, making CHD more likely
3. Mixture of chemicals in cigarette smoke leads to increased blood pressure

Question 10

How does binary fission work?

Answer 10

1. Binary fission is how prokaryotic cells reproduce asexually
2. The circular DNA and plasmids replicate
3. The cell gets bigger and the circular DNA strands move to opposite poles of the cell
4. The cytoplasm begins to divide and new cell walls begin to form
5. The cytoplasm divides and two daughter cells are produced
6. Each daughter cell has one copy of the circuar DNA but can have a variable number of copies of the plasmids

Question 11

Purpose of villi?

Answer 11

1. The inside of the small intestine is covered in millions and millions of tiny projections called villi
2. They increase the surface area in a big way so that digested food is absorbed much more quickly into the blood
3. They have a single layer of surface cells
4. They have a very good blood supply to assist quick absorption

Question 12

How are leaves adapted for photosynthesis?

Answer 12

1. Large surface area for light to fall onto
2. Thin so diffusion distances are short for gases
3. They contain chlorophyll in the choloroplasts to absorb light
4. They have guard cells that open and close the stomata to regulate gas exchange
5. They have veins that bring plenty of water in xylem to the cells of the leaves and remove the products of photosynthesis in the phloem

Question 13

How can chlorophyll be a limiting factor of photosyntehsis?

Answer 13

1. The amount of chlorophyll in a plant can be affected by disease or environmental stress such as lack of nutrients
2. These factors can cause chloroplasts to become damaged or not make enough chlorophyll
3. This means the rate of photosynthesis is reduced because they cant absorb as much light

Question 14

What is the purpose of a paraffin heater?

Answer 14

. As a paraffin heater burns, it makes carbon dioxide as a waste product
2. This is used to increase the level of carbon dioxide in the greenhouse