ACORN COLLEGE AS BIOLOGY UNIT 2 PRACTICE QUESTIONS NAME................................................................................................................................. 1. Read through the following passage on the structure of prokaryotic cells, then write on the dotted lines the most appropriate word or words to complete the account. Bacteria, such as Escherichia coli, are prokaryotic organisms. One of the main differences between prokaryotic cells and eukaryotic cells is that in a prokaryotic cell, the bacterial chromosome is not surrounded by a ............................................. . Prokaryotic cells store carbon compounds in the form of ............................................. and ................................................. and they may also contain one or more small circular DNA molecules, known as ................................................ . E. coli cells are motile due to the presence of a......................................................... .(Total 5 marks)

2.

The photograph below shows a section through a mitochondrion as seen using an electron microscope.

A

C

B

Prof. R. Bellairs/Wellcome Photo Library

(a)

Name the parts labelled A, B and C. A ................................................................................................................................ B ................................................................................................................................ C ................................................................................................................................(3)

Acorn College

1

(b)

Describe the role of mitochondria. .................................................................................................................................... .................................................................................................................................... ....................................................................................................................................(2) (Total 5 marks)

3.

(a) (i)

Independent assortment and crossing over both result in genetic variation. Explain how independent assortment leads to genetic variation. ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2)

(ii)

Describe how crossing over further increases genetic variation. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2)

(b)

The graph below shows changes in mean height of men in Japan from 1950 to 1980.1 1 7 7 3 2 t 2 0

M o f

e a n h m e n 1a / c m 1 1 1 1 1 1 1 1

e i g h 7g 1e d 7 6 6 6 6 6 6 6 1 9 0 9 8 7 6 5 4 3 4 5

1

9

5

0 Y e a r

1

9

5

5

1

9

6

0

1

9

6

5

Describe the changes in height between 1950 and 1980.

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

(c)

The graph below shows changes in the major components of the diet of men in Japan over the same period.R e la tiv e p r o p o r tio n o f d ie ta r y c o m p o n e n t / a r b itr a r y u n its 8 7 6 5 4 3 2 1 0 1 9 5 0 Y e a r 1 9 6 0 1 9 7 0 1 9 8 0 0 0 0 0 0 0 0 c a r b f a t a n i m a l p r o t e i n o h y d r a t e

0

The evidence from both graphs suggests that a combination of genetic and environmental factors influence the height of men in Japan. Give an explanation for this. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(4) (Total 10 marks)

4.

This question is about the preparation of a microscope slide that would enable you to see the stages of mitosis. (a) Name a suitable organism and tissue which could be used to study mitosis. (i) (ii) (b) organism .................................................................................................................(1)

tissue .......................................................................................................................(1)

Name a stain you might use to make the chromosomes visible. .....................................................................................................................................(1)

(c)Acorn College

Explain why the cells are warmed in acid during the preparation of the slide.3

..................................................................................................................................... .....................................................................................................................................(1)

(d)

The diagram below shows a chromosome during an early stage of mitosis. Write the names of the parts labelled A and B on the lines provided.A A B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

B

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

(2) (Total 6 marks)

5.

Agrostis tenuis is a grass that grows near old copper mines in North Wales. Copper is usually very toxic to plants, but some Agrostis plants can tolerate copper in the soil and grow on the waste tips from the copper mines. (a) Suggest a method for measuring tolerance to copper in a sample of Agrostis plants. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(2)

(b)

Agrostis plants were sampled from three sites close to a copper mine. Site B was on the waste tip from the mine, Site Awas up-wind of the tip and Site C was down-wind, as shown below. The tolerance to copper of each of the samples was measured and the results are shown in the graph below.

U N o

i n e Dw oa w t en - t wi p i n d s p - w i n d s C i t oe p p e r m s i t e c o p p e r p r C e os e p n p t e i r n p s r oe is N l e on t c i o n p s p o e i r l p r e s e n t

i n

s o

i l

S

i t e

A

S

i t e

B

S

i t e

C

M

a i n

w

i n

d

d

i r e c t i o

n

H

i g

h

T o l e r a n c e t o C o p p e r

L

o

w S i t e A S i t e B S

Suggest an explanation for the difference in tolerance between plants in the up-wind site (A) and plants in the down-wind site (C). ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(3)

(c)

Samples of tolerant and non-tolerant plants were grown in three trays of soil that contained no copper. Tray 1 contained only tolerant plants, Tray 3 contained only nontolerant plants and Tray 2 had a mixture of equal numbers of both types. The total dry mass of the plants in each tray was measured. The arrangement of the plants and the results are summarised below. 46 g ___ 12 g 30 g ___ 47 g

Total dry mass of tolerant plants Total dry mass of non-tolerant plants

Suggest an explanation for the results obtained in Tray 2. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................

Acorn College

5

..................................................................................................................................... .....................................................................................................................................(4)

(d)

Suggest and explain how the abundance of copper-tolerant Agrostis plants would be likely to change if the copper were removed from the soil on the mine waste tip (Site B). ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(2) (Total 11 marks)

6.

A freshwater stream was sampled over a distance of 4.0 km to determine the abundance of an aquatic invertebrate. The oxygen concentration of the water was measured over the same distance. The results are shown in the graphs below.

N u m b e r o f o rg a n is m s fo u n d a t e a c h s a m p lin g s ta tio n

100 50 0 0 1 .0 2 .0 D is ta n c e / k m 3 .0 4 .0

O x y g e n c o n c e n tr a tio n

0 (a)

1 .0

2 .0 D is ta n c e / k m

3 .0

4 .0

Name one aquatic invertebrate that might show this distribution along the stream. ..................................................................................................................................... .....................................................................................................................................(1)

(b)

Suggest two adaptations that would enable an invertebrate to thrive between 0.2 and 1.0 km along the stream. In each case state how the adaptation assists survival. 1................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... 2................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................

.....................................................................................................................................(4) (Total 5 marks)

7.

The photograph below shows a transverse section through part of a leaf of Nymphaea, as seen using a light microscope. Nymphaea is a hydrophyte (a plant which lives in water). The upper epidermis and air spaces are labelled.

(a)

Suggest one function of the tissue labelled A, giving an explanation for your answer. Function ........................................................................................................................ Explanation ................................................................................................................... ...................................................................................................................................... ...................................................................................................................................... ......................................................................................................................................(3)

(b)

Suggest two functions of the large air spaces in this leaf. 1 ................................................................................................................................... ...................................................................................................................................... 2 ................................................................................................................................... ......................................................................................................................................(2)

(c)

Suggest why stomata are found only in the upper epidermis of this leaf. ...................................................................................................................................... ...................................................................................................................................... ......................................................................................................................................(2) (Total 7 marks)

Acorn College

7

8.

A newspaper recently published the following report.

Scientists find gene to halt ovarian cancerA gene that can stop the development of cancer of the ovary has been identified. This gene acts as a tumour suppressor. If the gene is switched off then a tumour develops. Scientists have switched the gene back on in mice and the cancer cells stopped developing. Scientists hope to be able to find a drug to turn this gene back on. This could provide a means of treating ovarian cancer in humans. (a) (i) If a suitable drug is found it will have to be carefully tested in clinical trials. Describe the methods that would be used to trial a new drug to treat ovarian cancer. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(4)

(ii)

William Withering carried out trials of the digitalis soup which he used to treat patients. Explain why his methods could not be used as part of a modern clinical trial. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(2)

(b)

In the future, it may be possible to treat ovarian cancer by transplanting healthy stem cells into a diseased ovary. Some people think that stem cell research should not be carried out. State whether you are for or against the use of stem cells to treat ovarian cancer. For or against? ........................ Present an argument to explain why you hold this point of view (for or against) using

your biological knowledge of stem cell research and the ethical issues connected with it. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(3) (Total 9 marks)

9.

The diagram below shows the structure of a bacterium, a typical prokaryotic cell.

B C

A(a) Name A, B and C as labelled on the diagram. A ............................................................................................................................... B ............................................................................................................................... C ...............................................................................................................................(3)

(b)

Complete the table below to show three differences between a prokaryotic cell and a eukaryotic cell. Prokaryotic cell 1 2 3(3) (Total 6 marks)

Eukaryotic cell

10.

Many plants are grown for their fibres for use in making cloth. For example, nettle fibres can be9

Acorn College

used for this purpose. In the future nettle fibres may be developed in the United Kingdom as an alternative to imported cotton plant fibres. A student investigated the strength of plant fibres to find out if they could be made into cloth. The following method was used. Step 1. Step 2. Step 3. (a) Harvest nettle plants and remove leaves from stems Place stems in buckets and cover with water. Leave for ten days Remove stems and wash fibres under running water

Suggest and explain the changes that take place in the nettle stems during Step 2. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(2)

(b)

Describe a reliable method for measuring the strength of these plant fibres. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(4)

(c)

Suggest why, in the United Kingdom, cloth made from nettle fibres could be made more cheaply than cloth made from cotton. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .....................................................................................................................................(2) (Total 8 marks)

11.

Garlic is known to contain an antibacterial substance called allicin. (a) Suggest an advantage to a plant in producing antibacterial substances in its cells. ..................................................................................................................................... .....................................................................................................................................

(1)

Acorn College

11

(b)

The presence of antibacterial substances in garlic can be demonstrated by grinding garlic in ethanol to produce an extract. A sample of this extract is then applied to a small disc of filter paper. (i) Describe how you would demonstrate that this disc contained an antibacterial substance. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(4)

(ii)

A newly discovered rainforest plant is thought to contain a powerful antibacterial substance. Explain how you would compare the effectiveness of this new substance with allicin in garlic. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................(3)

(c)

Suggest how this newly discovered plant substance might have a useful application which does not involve genetic modification. ..................................................................................................................................... .....................................................................................................................................(1) (Total 9 marks)

12.

The diagram below shows a stage in the division of a cell from the male part of a flower. The diploid number of chromosomes for this plant is 14.

(a)

State the exact location of such a cell in the male part of a flower. ......................................................................................................................................(1)

(b)

Identify the stage of meiosis shown in the diagram. ......................................................................................................................................(2)

(c)

Fertilisation in a plant involves different types of cells and nuclei. State the number of chromosomes present in each of the following in this plant. A pollen tube nucleus .......................... A female gamete (egg cell) ................. A zygote nucleus ................................. An endosperm cell ...............................(4) (Total 7 marks)

13.

The diagram below shows the structure of a bacterial cell as seen using an electron microscope. C e l l w a l lS t o r a g e g r a n u B l e

A

X

Y

Acorn College

13

(a)

(i)

Name the parts labelled A and B.

A ............................................................................................................................ B ............................................................................................................................(2)

(ii)

Name the carbohydrate present in the storage granules. ...............................................................................................................................(1)

(iii)

Describe how the cell wall in this bacterial cell differs from that in a plant cell. ............................................................................................................................... ...............................................................................................................................(1)

(b)

The diagram has been magnified 6000 times. Calculate the actual length of the bacterial cell between X and Y. Show your working, and give your answer in micrometres.

Answer ............................. m(3) (Total 7 marks)

14.

The diagram below shows part of a transverse section at high magnification through a seminiferous tubule in human testis.

(a)

Identify cells B and C. B .............................................................................................................................. C ..............................................................................................................................(2)

(b)

(i) Give the letter of one cell with the haploid (n) number of chromosomes. (1)

(ii)

Explain how meiosis results in the production of haploid cells. (4)

(c)

Give two features of a spermatozoon that enable it to carry out fertilisation. Explain in each case how these features assist in fertilisation. .. .. .. ..(2) (Total 9 marks)

15.

Read through the following account relating to some carbohydrates in plants, then write on the dotted lines the most appropriate word or words to complete the account. Starch is made from the monosaccharide ....................................... whereas cellulose is made from the monosaccharide ....................................... . Polysaccharides are formed when ....................................... monosaccharides join together using ....................................... bonds. Starch is ....................................... in water and can therefore be used to store ....................................... . Cellulose molecules are held together in parallel groups by ....................................... bonds.(Total 7 marks)

16.

An investigation was performed to determine the length of time that a cell in an onion root tip spends in each stage of mitosis. A growing root from an onion was selected and a root tip squash was made. This was examined

Acorn College

15

under a light microscope and the percentage of cells in each stage of mitosis was determined. The results are shown in the table below. Stage of mitosis Prophase Metaphase Anaphase Telophase (a) Percentage of cells in this stage 2.43 1.40 0.70 2.78

Describe how you would prepare a root tip squash so that mitosis could be studied. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... .......................................................................................................................................(4)

(b)

The percentage of cells in a stage of mitosis is proportional to the duration of that stage. Use this information to compare the duration of each stage of mitosis in these root tip cells. ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... .......................................................................................................................................(3)

(c)

The duration of each stage of mitosis can be calculated using the equation below.

Percentage of cells in that stage cell cycle time 100 Duration of a stage =The cell cycle time for these cells is 1200 minutes. Describe how you would use this data to determine the total duration of mitosis.

....................................................................................................................................... ....................................................................................................................................... ....................................................................................................................................... .......................................................................................................................................(2) (Total 9 marks)

17.

The siting of a new sewage treatment works and the discharge of its effluent need careful consideration in order to minimise ecological damage. Figure 1 shows two possible sites for a new sewage works near to the coast in North Devon. Figure 1 Plan of proposed sites for sewage treatment works, underground pipelines and marine discharge pipelines

Site 2

p = field q = field r = field s = cliff grassland t = rocky shore

Site 1

a = field b = conservation area

This development would involve the permanent siting of the buildings for the main sewage treatment plant, an underground pipeline and a marine discharge pipe. A strip of land 10 metres wide would need to be removed during the laying of the underground pipeline. The land would be returned to its previous condition after the work is completed. An ecological assessment must be carried out before any development can go ahead. The assessment compares the possible effects of the development on the terrestrial areas of the two sites. The first stage is to assign each area to a particular ecological category, using the criteria in Figure 2.Acorn College 17

Figure 2 Criteria for assigning ecological categories to an area Criteria Very high species diversity and highest number of different habitats or rare habitats Ecological category 5

Very low species diversity and lowest number of different habitats or rare habitats

1

The second stage is to calculate the impact of the proposed development within each area using the following formula: area (m ) ecological category = units of damage Finally, consideration is given to whether the damage is reversible or irreversible. Figure 3 shows the results of this ecological assessment survey for Site 1 and Site 2.2

Figure 3 A comparison of the results of the ecological assessment survey for Site 1 and Site 2 Site 1 Area a b* Type of development Building Pipeline Area/m2

Ecological category 2 5 Totals

Units of damage 21 000 750 000 771 000 Site 2

Reversible damage 750 000 750 000

Irreversible damage 21 000 21 000

10 500 150 000

Area p q* r* s* t*

Type of development Building Pipeline Pipeline Pipeline Pipeline

Area/m

2

Ecological category 2 1 1 5 5 Totals

Units of damage

Reversible damage

Irreversible damage

21 000 2 500 3 000 500 2 000

10 000

* involves laying of underground pipeline only.Data adapted from JBE Vol 32 Number 2 Summer 1998

(a)

Suggest why some damage is considered to be reversible and some damage is considered to be irreversible. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................(2)

(b) (c)

Complete the data for Site 2 in Figure 3.(3)

Using the data in Figure 3, compare the ecological effect that the development of the sewage treatment works would have at Site 1 and Site 2. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................(3)

(d)

State what is meant by species diversity. ............................................................................................................................................ ............................................................................................................................................(1)

(e)

The ecological impact on the marine environment also needs to be considered. Using information from Figure 1, suggest three factors affecting the marine environment that should be considered when comparing Site 1 with Site 2. 1 ... 2 ... 3 ...(3)

(f)

Suggest why an accidental discharge of raw sewage from the treatment works might lead to an increase in the numbers of carnivorous fish around the discharge pipe. ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................ ............................................................................................................................................(4) (Total 16 marks)

Acorn College

19