Cambridge IGCSE Biology - 0610 - Supplement Paper 4 2017 Winter Zone 2

The lungs and the kidneys are part of the excretory system of mammals.
(a) (i) State the name of one substance that is excreted from the lungs and state where in the body it is produced.
name ..........................................................................................................................
site of production ........................................................................................................
[2]
(ii) State the name of one excretory substance, that is removed by the kidneys, that contains nitrogen.
Explain why it is excreted.
name ..........................................................................................................................
explanation ..................................................................................................................
.................................................................................................................................
[2]
(b) Blood is filtered as it flows through the kidneys.
(i) State the name of the structure within a kidney that filters the blood.
................................................................................................................................. [1]
(ii) State two components of blood that do not pass through the filter.
1 .................................................................................................................................
2 .................................................................................................................................
[2]
(c) The filtrate which is formed from the blood in the kidneys contains many useful substances, which are reabsorbed into the blood.
Fig. 1.1 is a photomicrograph of a cross-section of some of the cells that carry out reabsorption.

(i) Complete the table by stating the letter in Fig. 1.1 that identifies each structure.

A person who wanted to begin a fitness programme did some vigorous exercise.
A fitness trainer took a drop of blood from the person’s finger before, during and after vigorous exercise and tested it for lactic acid.
(a) Explain why it is important that the equipment used for taking blood is clean (sterile).
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................[2]
(b) The results of the tests for lactic acid are shown in Fig. 2.1.

Describe and explain the changes in blood lactic acid concentration shown in Fig. 2.1.
...........................................................................................................................................................
...........................................................................................................................................................
...........................................................................................................................................................
...........................................................................................................................................................
...........................................................................................................................................................
...........................................................................................................................................................[6]
(c) The concentration of lactic acid in the blood of two athletes was investigated. One athlete, P, had been training and the other, Q, was returning to training after an injury.
Blood samples were taken from both athletes during a training session. The results are shown in Fig. 2.2.

(i) The lactic acid threshold is the level of exercise where the lactic acid concentration begins to increase exponentially.
State the lactic acid threshold for athletes P and Q.
P .............................................. km h$^{-1}$
Q .............................................. km h$^{-1}$ [1]
(ii) Suggest a reason for the difference in lactic acid threshold of athletes P and Q.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................[1]
(iii) Explain the link between physical activity and breathing.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................[4]

(a) Describe the \textit{trend} in the population of sheep in Tasmania between 1820 and 1940, using the information in Fig. 3.1.
................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................[3]

(b) Explain the change in the \textit{trend} of the population that you described in 3(a).
..............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................[3]

(c) The sheep that were first introduced to Tasmania were not well adapted to the environment.
Describe how farmers can use selective breeding to improve their sheep so that they are better adapted to the environment.
................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................[4]

(d) Maintaining very large populations of farm animals is unsustainable.
Define the term \textit{sustainable development}.
........................................................................................................................................................................................................................................[2]

The garden pea, Pisum sativum, is a plant which has flowers that have both male and female parts. P. sativum is naturally self-pollinating.
(a) Discuss the advantages and disadvantages of self-pollination.
..................................................................................................................................................................................
..................................................................................................................................................................................
..................................................................................................................................................................................
..................................................................................................................................................................................
..................................................................................................................................................................................
..................................................................................................................................................................................
.................................................................................................................................................................................. [4]

(b) Gregor Mendel studied inheritance in the garden pea, P. sativum.

The flowers of P. sativum that he studied were either purple or white. The gene that controls flower colour has two alleles, B and b.

When Mendel crossed purple-flowered plants with white-flowered plants all the plants in the next generation had purple flowers.

(i) Table 4.1 shows five genetic terms that can be applied to Mendel’s study of the inheritance of flower colour.

Complete Table 4.1 by stating an example of each genetic term. The first one has been completed for you.

[Table 4.1]
| term | example in P. sativum |
|-----------------------|-------------------------|
| dominant trait | purple flowers |
| recessive allele | |
| phenotype | |
| homozygous genotype | |
| heterozygous genotype | |
[4]

(ii) Test crosses can be used to determine the genotype of a plant with purple flowers.

The genetic diagrams show test crosses for purple-flowered plants with two different genotypes.

Complete the genetic diagrams for test cross 1 and test cross 2.



test cross 1 test cross 2
parental phenotype purple flowers × white flowers purple flowers × white flowers
parental genotype Bb × ................................ BB × ...............................
genotypes of gametes (........)(........) + (........)(........) (........)(........) + (........)(........)
offspring genotypes ................................................ ................................................
offspring phenotypes .............................................. .............................................. [5]

(c) Pickerel weed, Pontederia cordata, is a plant that grows in shallow water on the edges of ponds and lakes in North America.

A few seedlings of these plants are white. The white seedlings cannot make chlorophyll.

Researchers carried out several crosses using pickerel weed plants.

Their results are shown in Table 4.2.

[Table 4.2]
| cross | number of offspring | |
|-------|---------------------|--------|
| | green | white |
| 1 | 149 | 0 |
| 2 | 70 | 22 |

(i) Select suitable symbols for the alleles and state the possible genotypes of the parents for each cross.

cross 1 ...........................................................................................................................
cross 2 ........................................................................................................................... [2]

(ii) It is not possible to carry out a test cross with pickerel weed plants.

Suggest why.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
................................................................................................................................. [2]

Fig. 5.1 shows the bacterium Helicobacter pylori, which is a human pathogen.

(a) State the genus of Helicobacter pylori. [1]

(b) H. pylori is placed in the prokaryote kingdom.

State two structural features that H. pylori shares with other prokaryotes. [2]

(c) (i) H. pylori can cause infections in the stomach. Suggest how this infection could be treated. [1]

(ii) State one natural body defence that is found in the stomach. [1]

(d) The immune system is not very effective against pathogens, such as H. pylori, that live inside the alimentary canal. This means that active immunity and passive immunity do not provide complete protection against H. pylori infections.

Explain how active immunity differs from passive immunity. [4]

(a) Complete Table 6.1 by naming the blood vessels labelled on Fig. 6.1 and stating whether they contain oxygenated blood or deoxygenated blood. One row has been completed for you.

[Table_6.1]

(b) Insulin is a hormone that is secreted by the pancreas.
(i) Define the term hormone.

.................................................................
..................................................................
..................................................................
..................................................................
...............................................................................................[2]

(ii) Describe the role of insulin in the body.

..................................................................
..................................................................
..................................................................
..................................................................
..................................................................[3]

(c) Explain how blood flow in the skin helps to maintain a constant body temperature in very hot conditions.

..................................................................
..................................................................
..................................................................
..................................................................
..................................................................[3]