Biology Home learning

Home learning (1)- Past paper questionsName: Due:

1. Scientists measured the amount of energy used by four people, A, B, C and D. The scientists also measured the amount of energy taken in as food by each person. The chart shows the scientists’ results.

a. (i) What was the mean amount of energy used by D?...................................................................... kJ per day

(1 mark) (ii) The amount of energy used by D is different from the amounts of energy used by A, B and C.Suggest two reasons why.....................................................................................................................................................................................................................(2 marks)(b) The data in the bar chart was collected over twelve months.Which person, A, B, C or D, would gain body mass over the twelve months? Give a reason for your answer.

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.................................................................................................................................................. ............................................................................................................................... (2

marks)(c) In the UK many people are obese. Doctors advise obese people to lose mass.

Suggest two different ways an obese person could lose mass.

..................................................................................................................................................... ................................................................................................................................ (2

marks)

Home learning (2)- Growing bacteria Name: Due:1. Some students investigated the effect of pH on the growth of one species of bacterium.

They transferred samples of bacteria from a culture of this species to each of eight flasks. Each flask contained a solution of nutrients but at a different pH.After 24 hours, the students measured the amount of bacterial growth.

a)It was important that the flasks in which the bacteria grew were not contaminated with other microorganisms.Describe two precautions the students should have taken to prevent this contamination.1.......................................................................................................2....................................................................................................... (2 marks)(b) To see the effect of pH on the growth of the bacteria, other conditions should be kept constant.Suggest two conditions which should have been kept constant for all eight flasks.1.............................................................................................................2.............................................................................................................. (2 marks) (c) The students wanted to find the best pH for the

growth of this species of bacterium.(i) Use the graph to estimate the pH at which the bacteria would grow best.pH .............................. (1 mark)(ii) What could the students do to find a more accurate value for the best pH for growth of the bacteria?..................................................................................................... (1 mark)

1. An investigator placed paper discs containing different concentrations of an antibiotic onto a culture of bacteria in a petri dish. After an incubation period of two days, the dish looked like this:

Home learning (3)- Antibiotics Name: Due:

(a) Which antibiotic disc is the most effective at killing this strain of bacteria?……………………………… (1 mark)

(b) Explain why there are areas around some of the paper discs where no bacteria are growing.

......................................................................

......................................................................

................ (2 marks)

Disc Concentration of the antibiotic

in units

Diameter of circle where no bacteria

are growing, in mm

A 0 0

B 2 8

C 4 14

D 6 26

E 10 26

2. The concentration of the antibiotic on the

paper discs is given in the table, along with the

diameter of the circles where no bacteria are

growing.

(a) What effect does an increase in the concentration of the antibiotic have on the growth of the bacteria?

……………………………………………………………………………………………………………………………………… (2 marks)

Higher question: 3. Scientists are concerned that many bacteria are developing resistance to antibiotics. Suggest two ways by which this problem could be limited...................................................................................................................................................................................................................................................................... (2 marks)

1. The graph shows the number of people with measles in the UK between 1940 and 2010.

Home learning (4)- Antibiotics Name: Due:

b. Compare how effective introducing the measles vaccine was with introducing the MMR vaccine. Use data from the graph.

………………………………………………………………………………………………………………………………………………………………………………………………………………………………..…………………………………………………………………(3 marks)

a) The MMR vaccine was introduced in 1988. Other than measles, which two diseases does the MMR vaccine protect against?

1...................................... 2 .....................................(2 marks)

(c) To immunise someone against measles, a small quantity of the inactive measles pathogen is injected into the body. Describe what happens in the body after immunisation to stop a person catching measles in the future. …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………..(3 marks)