EXAM

Question 1

Explain what steps are taken to ensure a modern drug is valid

Answer 1

1. Double blind trials are used to eliminate bias
2. Large sample size so statistical tests can be done to show the effects of the drug
3. Control groups that receive a placebo are included to allow comparisons to be made between the control group and the group getting the drug

Question 2

Explain why drugs are tested on animals and then on humans in a modern drug trial

Answer 2

1. Tested on animals for toxicity and safety

2. Then it is tested on humans to look for side effects and efficacy

Question 3

Explain the difference between treatment and a vaccine for a disease such as ebola

Answer 3

A vaccine will prevent the disease before someone has it whereas a treatment will cure a disease once someone has it

Question 4

What is more useful to develop a vaccine or treatments

Answer 4

in the long term it is better to have a vaccine as the whole population can be protected from from the effects of the disease (herd immunity) if an outbreak occurs not that many people will be affected

Treatment can cure people but only once people have the disease it is better to prevent it so no one gets it

Question 5

What is the best way to control the spread of Ebola

Answer 5

B- the hygenic disposal of faecal material

Question 6

Ebola is caused by a virus and is extremely difficult to treat. It is being tackled by preventing its spread. Use the relevant facts above to explain strategies to prevent its spread

Answer 6

1. Due to the incubation period any person who has been in contact with a victim need to be isolated for a minimum of three weeks to contain the spread
2. Due to droplet infection risk people should stay in well ventilated areas and wear masks
3. Hand washing
4. Appropriate preparation of bodies for burial to minimise the chance of contact the person should wear a mask and gloves

Question 7

In insects blood flows out of the blood vessels and into the body cavity. This is known as

Answer 7

An open circulatory system

Question 8

What are the advantages of chitinuous hoops in tracheae

Answer 8

They support the trachaea and keep them open whilst the insect is moving

Question 9

What are the advantages of closable spiracles in body segments

Answer 9

They control the rate of gas exchange and allow the insect to conserve water

Question 10

What are the advantages of abdominal pumping movements

Answer 10

Mechanically increases gas exchange and pumps air into the system increasing oxygen supply

Question 11

What are the advantages of non-chitinous tracheoles

Answer 11

Allows gas exchange as chitin is impermeable to gases

Question 12

Describe how insects take oxygen into their bodies

Answer 12

1. Oxygen from the air diffuses into the respiratory system via the spiracles and into the trachae.
2. The tracheae branch into tracheoles that have fluid inside of them the oxygen then diffuses into the fluid and into the insects cells

Question 13

Explain the appearance of the cells labelled A,B and C

Answer 13

A= The red pigment is in the vacuole and not in the rest of the cell the cell is hypertonic to the cell solution

B= Same but less red pigment in this cell than originally in the vacuole

C= Same but no red pigment in this cell

Question 14

Deduce the turgor pressure that you will find in cell A and Explain your answer

Answer 14

Zero turgor pressure as the turgor pressure is the force applied by the cell wall on the cell due to it being filled with water.

However as the cell has lost a lot of water the cell wall does not push on the cell

Question 15

State the name given to the appearance of Cell A

Answer 15

Plasmolysed

Question 16

State the part of a nephron which is affected by ADH

Answer 16

collecting duct

Question 17

Explain the effect that increased ADH levels would have on the concentration of the filtrate

Answer 17

1. Increased ADH increases the aquaporins that attach tot he collecting duct
2. This means more water molecules would move out of the collecting duct by osmosis
3. This leads to a more concentrated filtrate

Question 18

State which of the nephrons A,B or C would create a higher concentration of urine

Answer 18

C

1. The longer loop of henle produces a lower water potential in the medulla
2. In the counter current multiplier more sodium ions would be being actively transported out of the ascending limb
3. More water molecules would move out of the collecting duct by osmosis

Question 19

Name two molecules that can be produced from this amine group

Answer 19

ammonia and urea

Question 20

Glucose moleucles can be turned into a polysaccharide for storage in cells. Name this polysaccharide and explain how it is formed from glucose

Answer 20

Glycogen

Condensation reactions joining alpha glucose monomers together via 1-6 and 1-4 glycosidic bonds

Question 21

Explain how the changes in concentration of the substances are brought about by the kidney

Answer 21

1. Ultra filtration occurs in the glomerulus
2. The filtrate passes into the bowmans capsule
3. Blood cells and large proteins are too big to pass through the gaps in the capillary walls so no proteins will be found in the filtrate .
4. All the amino acids and the glucose molecules are actively transported in the proximal convoluted tubule. Active transport required energy from ATP . This means no amino acids and glucose molecules will be leaving the collecting duct
5. Water is reabsorbed back into the blood via the collecting duct meaning there will be a higher concentration of urea and ions in the urine than in the filtrate

Question 22

Explain what happens to the energy reaching producers that is not converted to growth during photosynthesis

Answer 22

Some energy will be used to evaporate water on the leaves or some of the light will be the wrong wavelength or not reach the chloroplasts

Question 23

Give four reasons why the rain forest has a greater GPP than the pine forest

Answer 23

1. Rate of photosynthesis is higher due to higher temperatures
2. Longer days averaged over a year/ more sunlight
3. Plant density is lower in pine forests

Question 24

Explain the meaning of the term GPP

Answer 24

GPP is the gross primary production and the total amount of energy in organic molecules trapped by photosynthesis per unit area per unit time

Question 25

Suggest how a farmer who wanted to use this land for cattle might use this information

Answer 25

Cattle are primary consumers so gain energy from NPP the farmer needs to ensure there is sufficient NPP available for all cattle or yield will be reduced

Question 26

The units used in the diagram kj/m2/yr show a rate of energy production. Suggest why this is more useful than measurements of biomass in the grassland on a particular day

Answer 26

This gives an average value for the whole year as the biomass changes depending on the season

Question 27

The farmer had another pasture with a different grass species. Here the GPP was 10800 kj suggest why the GPP is greater here than in the field mentioned above

Answer 27

This grass has a higher rate of photosynthesis as there are more nutrients in the soil ;

Question 28

At a recent scientific conference there was a debate as to whether two beetles which had identical morphology but occurred in two very different habitats were actually two different species. How would you investigate this issue by using reproduction

Answer 28

1. Take the organisms some have to be mature females and some males and place them in a closed environment with optimum conditions such as temperature for them to reproduce
2. They will need to produce fertile offspring which survive and later on go on to produce fertile offspring when they become mature