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(a) Fig. 1.1 shows the human head, neck and thorax. [Image_1: Fig. 1.1 Diagram]
Complete Table 1.1 by writing one letter from Fig. 1.1 to identify the named structures. The first one has been done for you.
[Table_1: Table 1.1]
- structure: left lung, letter from Fig. 1.1: D
- structure: bronchus
- structure: diaphragm
- structure: intercostal muscle
- structure: rib
- structure: trachea
(b) In an investigation, a student breathed in and out of the apparatus shown in Fig. 1.2.
[Image_1: Fig. 1.2 Diagram]
Valve X opens to allow atmospheric air in while valve Y is closed.
When the student breathes out, valve X is closed and valve Y opens to allow breathed out air into the bag.
The student breathed in and out four times. The bag was sealed and the volume of air inside the bag was measured.
A sample of air from the bag was analysed for the percentage composition of oxygen, carbon dioxide and nitrogen.
The student then did some vigorous exercise for five minutes. After the exercise, the student repeated the procedure.
The results of the investigation are shown in Table 1.2.
[Table_2: Table 1.2]
- sample of breathed out air before exercise: total volume of air collected in bag / cm$^3$: 2000
- sample of breathed out air after exercise: total volume of air collected in bag / cm$^3$: 15000
- mean volume of air per breath / cm$^3$: 500
- percentage of oxygen / %: 17.2 before exercise, 15.3 after exercise
- percentage of carbon dioxide / %: 3.6 before exercise, 5.5 after exercise
- percentage of nitrogen / %: 74.9 before exercise, 74.7 after exercise
(i) Calculate the mean volume of air per breath after exercise.
Write your answer in Table 1.2. Show your working. [1]
(ii) Suggest one way, not shown in Table 1.2, in which the student’s breathing changed after exercise. [1]
(iii) The figures in Table 1.2 for the percentage composition of air in each sample do not add up to 100 %.
Name one other gas that would be present in both samples of air. [1]
(iv) The results for oxygen and carbon dioxide in the samples of breathed out air taken before and after exercise are different.
Describe and explain these differences. [3]
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(a) The letters L to O represent the different trophic levels in the ecosystem.
(i) Name the first and third trophic levels, L and N.
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(ii) Suggest what is shown by the relative sizes of the boxes, L to O, in the energy flow diagram in Fig. 2.1.
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(iii) There are no predators in the ecosystem feeding on the animals in trophic level O.
Suggest and explain why there are no predators in the ecosystem feeding on the animals in trophic level O.
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[3]
(iv) P in Fig. 2.1 does not represent any organisms.
Explain what P represents in the energy flow diagram.
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(b) People who live near this ecosystem would like to use some of the organisms at trophic level M for food.
Suggest and explain what might happen to the ecosystem if the people took too many of the organisms at trophic level M.
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Fig. 3.1 shows the human female reproductive system.
(a) Table 3.1 shows four functions of the female reproductive system.
Complete the table by:
• naming the part of the system that carries out each of the functions;
• using the letters from Fig. 3.1 to identify the part of the system named.
One row has been completed for you.
Table 3.1
| function | name of organ | letter from Fig. 3.1 |
|-----------|----------------|----------------------|
| production of gametes | | |
| site of implantation | | |
| site of fertilisation | | |
| dilates during birth | cervix | V |
(b) (i) State the target organ of FSH.
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(b) (ii) State one effect of FSH.
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(c) The drug clomiphene is given to women who have difficulty in having children. The drug increases the secretion of FSH.
As part of treatment for infertility, a woman was given clomiphene for five days. The concentration of oestrogen in her blood was measured every day for 27 days.
The results are shown in Fig. 3.2.
(i) Describe the changes in oestrogen in the blood over the 27 days.
You will gain credit if you use results from Fig. 3.2 in your answer.
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(c) (ii) Doctors thought that ovulation occurred around day 15.
Explain what is meant by the term ovulation.
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(d) The treatment was not successful on the first occasion.
As an alternative to this treatment, women may be offered in vitro fertilisation (IVF) treatment.
In IVF treatment, an egg is fertilised outside the body and the resulting embryo is placed into the uterus.
Describe what happens when an egg is fertilised by a sperm.
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(e) (i) Some embryos produced by IVF do not develop because there are problems with their chromosomes, such as having the wrong number.
Define the term chromosome.
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(e) (ii) State the correct number of chromosomes that should be in a cell of a human embryo.
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Fig. 4.1 shows a cross section of part of a stem of buttercup, Ranunculus.
Fig. 4.2 is an outline drawing of one vascular bundle from the stem of Ranunculus.
(a) Draw and label the position of the xylem and the phloem in the outline of the vascular bundle in Fig. 4.2. [2]
(b) Name the carbohydrate that is transported in the phloem. [1]
(c) Substances transported in the phloem are carried upwards in the stem at some times of the year and downwards at other times.
Explain why substances are transported in the phloem upwards at one time of the year and downwards at another. [4]
(d) Define the term transpiration. [3]
(e) The rattan palm is a plant that climbs on rainforest trees to heights of about 40 metres.
Explain how water is moved to the tops of tall plants, such as the rattan palm. [4]
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Enzymes are necessary for many biological processes, such as the digestion of fat. $$ \text{fat + water} \xrightarrow{\text{lipase}} \text{fatty acids + glycerol} $$ (a) (i) Explain why enzymes are necessary for biological processes. ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... [3] (ii) Lipase, protease and amylase are enzymes secreted into the alimentary canal. Name \textit{one} organ that secretes each enzyme. Choose your answers from this list. \text{colon\newline gall bladder\newline liver\newline oesophagus\newline pancreas\newline rectum\newline salivary glands\newline stomach} You can use each organ \textit{only once}. \textbf{lipase} .......................................................................................................................................................\newline\textbf{protease} .......................................................................................................................................................\newline\textbf{amylase} ....................................................................................................................................................... [3]
(b) A group of students investigated the digestion of fat in milk. • They added an alkaline solution to the milk.
• They divided the milk into four test-tubes.
• They added lipase and bile salts to some of the test-tubes, as shown in Table 5.1. They did this at the same time for each test-tube.
• They kept all test-tubes at 40 °C.
• After 5 minutes, they added Universal Indicator solution to each test-tube. \begin{table} test-tube & contents & colour of pH indicator after 5 \newline minutes at 40 °C \hline A & milk, alkaline solution, lipase and bile salts & orange \newline B & milk, alkaline solution, bile salts and & blue \newline & water \newline C & milk, alkaline solution, lipase and & yellow \newline & water \newline D & milk, alkaline solution and water & blue \end{table} Fig. 5.1 shows the colour of the indicator at different pH values. \begin{align*} \text{red} & \quad \quad \quad \quad \quad \quad \quad \quad \text{orange} \quad \quad \quad \quad \quad \quad \quad \quad \text{yellow} \quad \quad \quad \quad \quad \quad \quad \quad \text{green} \quad \quad \quad \quad \quad \quad \quad \quad \text{blue} \quad \quad \quad \quad \quad \quad \quad \quad \text{purple} \newline 0 \quad \quad & 2 \quad \quad \quad \quad \quad \quad \quad \quad 4 \quad \quad \quad \quad \quad \quad \quad \quad 6 \quad \quad \quad \quad \quad \quad \quad \quad 8 \quad \quad \quad \quad \quad \quad \quad \quad 10 \quad \quad \quad \quad \quad \quad \quad \quad 12 \quad \quad \quad \quad \quad \quad \quad \quad 14 \end{align*} \text{Fig. 5.1} (i) Explain why test-tube D was included in the investigation. ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... [2] (ii) Explain why the colour in test-tube \textbf{A} was orange. ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... [3] (iii) Explain the results for test-tubes \textbf{B} and \textbf{C}. \newline \text{test-tube B} ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... \newline \text{test-tube C} ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... ....................................................................................................................................................... [4]
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Bacteria and animals are found in many habitats on land and in the sea.
(a) State two ways in which the structure of a bacterial cell differs from the structure of an animal cell.
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(b) Some bacteria were grown in the laboratory. Fig. 6.1 shows the change in numbers of bacteria when grown in a closed flask containing nutrients and oxygen.
(i) Name the phases of growth, A and B.
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(ii) Explain why the numbers of bacteria do not change in phase D and decrease in phase E.
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(c) Fig. 6.2 shows the vent crab, Bythograea thermydron, which lives at great depths in the sea where there is no light.
(i) State one feature, visible in Fig. 6.2, that show that B. thermydron is an arthropod.
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(ii) Although most species of crabs are red, brown or green, B. thermydron is white.
Suggest and explain how white crabs evolved at great depths in the sea.
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