Edexcel IAL Biology AS Topic 4 Questions

[Maximum number: 3]

Female mosquitoes feed on the blood of other animals to promote the development of their eggs. During this process, infected mosquitoes can transmit the Plasmodium parasite.

The Plasmodium parasite causes the disease malaria.
The photograph shows a female Anopheles mosquito.

Figure for Question 1 — Edexcel A-Level Biology AS

The fungus Metarhizium pingshaense infects Anopheles mosquitoes.

A student drew a labelled diagram of a fungal cell that was dividing.

Give three differences in ultrastructure between this cell and a cell taken from the root of a plant.

[Maximum number: 5]

A plant contains several types of cells, tissues and organs.

(a)

The photograph shows part of a cell.

Figure for Question (a) — Edexcel A-Level Biology AS

[ 2 ]

(i)

Which organelle is labelled X ?

A

chloroplast

B

endoplasmic reticulum

C

Golgi apparatus

D

plasmodesmata

[ 1 ]

(ii)

Organisms can be classified into three domains.

State which of the three domains would contain an organism with the organelles X and Y .

[ 1 ]

(b)

The drawing shows tubers of a potato plant developing below the surface of the soil.

Figure for Question (b) — Edexcel A-Level Biology AS

Organic molecules are transported through the potato plant to the developing tubers. These molecules can be used to form starch molecules.

[ 3 ]

(i)

Which structure in the cells of these tubers would store starch molecules?

A

amyloplast

B

chloroplast

C

middle lamella

D

vacuole

[ 1 ]

(ii)

Explain how the structure of starch enables the potato tubers to have a high energy content.

[ 2 ]

[Maximum number: 4]

Plants and animals are made of cells.

(a)

Starch can be stored in different parts of a plant cell.

[ 4 ]

(i)

Which of these parts of a plant cell store starch?

A

amyloplast only

B

amyloplast and chloroplast only

C

amyloplast and vacuole only

D

amyloplast, chloroplast and vacuole

[ 1 ]

(ii)

Describe the structure of starch.

[ 3 ]

[Maximum number: 1]

A plant contains several types of cells, tissues and organs.

The photograph shows part of a cell.

Figure for Question 4 — Edexcel A-Level Biology AS

Which organelle is labelled X ?

A

chloroplast

B

endoplasmic reticulum

C

Golgi apparatus

D

plasmodesmata

[Maximum number: 3]

Plants and animals are made of cells.

Starch can be stored in different parts of a plant cell.

Describe the structure of starch.

[Maximum number: 4]

Abaca plants are found in the Philippines.
The photograph shows a mat made from abaca plant fibres.

Figure for Question 6 — Edexcel A-Level Biology AS

Plant fibres include xylem vessels.

Explain how the arrangement of cellulose molecules and secondary thickening in xylem vessels contributes to the physical properties of the cell wall.

[Maximum number: 2]

Fibres from the stems of hemp plants are widely used in industry for their great tensile strength.

The relationship between tensile strength and fibre diameter was investigated.
The photograph shows a cross section of a part of a hemp fibre and an eyepiece graticule. The fibre bundle is made up of pith cells, some of which are shown here.

Figure for Question 7 — Edexcel A-Level Biology AS

(Source: © Ted Kinsman/SCIENCE PHOTO LIBRARY)

Name the two types of tissue found in fibres from plant stems.

1

[Maximum number: 8]

A student used a microscope to study the tissues in a plant stem and the cell of an animal.

The photograph shows a vascular bundle in a transverse section of the plant stem, as seen using a light microscope.

Figure for Question 8 — Edexcel A-Level Biology AS

(a)

Describe how you would use the information in the photograph to identify structures A and C .

[ 2 ]

(b)

A longitudinal section was taken through one of the labelled tissues A, B or C. The photograph shows a view of some of the cells in this tissue, as seen using a light microscope.

Deduce which of the tissues A, B or C these cells come from.

[ 3 ]

(c)

In another part of the investigation, a plan of the tissues in the stem was drawn.

Figure for Question (c) — Edexcel A-Level Biology AS

Describe how a thin section of a stem could be prepared and viewed using a light microscope, in order to draw this plan.

[ 3 ]

[Maximum number: 2]

Boards used for chopping fruit and vegetables can be made from wood or oil-based plastics.

The photograph shows some chopping boards.

Figure for Question 9 — Edexcel A-Level Biology AS

Explain why boards made from oil-based plastics are not considered sustainable.
(2)

[Maximum number: 5]

- -

- -

- -

(a)

The nutrient solutions contain magnesium ions and nitrates.

Describe the roles of these inorganic ions in the plants.

Magnesium ions

Nitrates

[ 2 ]

(b)

Fruits contain cells.

The effect of calcium ion concentration on the firmness of fruits was investigated.
Cherry plants were treated once, twice or three times, with two different concentrations of calcium chloride solution. The firmness of the cherry fruits from these plants was then measured.

The table shows the effect on the mean fruit firmness of these treatments and a control.

Table for Question (b) — Edexcel A-Level Biology AS

[ 3 ]

(i)

Explain the effect of calcium ion concentration on the firmness of cherry fruits.
(3)

[ 3 ]

[Maximum number: 7]

Fibres from the stems of hemp plants are widely used in industry for their great tensile strength.

The relationship between tensile strength and fibre diameter was investigated.
The photograph shows a cross section of a part of a hemp fibre and an eyepiece graticule. The fibre bundle is made up of pith cells, some of which are shown here.

Figure for Question 11 — Edexcel A-Level Biology AS

(Source: © Ted Kinsman/SCIENCE PHOTO LIBRARY)

(a)

The diagram shows apparatus that was used in an investigation to find the tensile strength of hemp fibres.

[ 7 ]

(i)

Describe how you could use this apparatus to make a valid comparison of the tensile strength of fibres with different diameters.

[ 4 ]

(ii)

Describe the relationship between the diameter and the tensile strength of these fibres.

[ 3 ]

An answer including three of the following points :

- the larger the diameter the less tensile strength / negative correlation (1)

- non-linear (1)

- steepest decrease {between $21 \mu \mathrm{~m}$ and $25 \mu \mathrm{~m} / \mathrm{up}$ to $25 \mu \mathrm{~m}$ } (1)

- less steep from $\{25-81 \mu \mathrm{~m} / 81-84 \mu \mathrm{~m}\}$ (1)

Accept reverse

(3)

[Maximum number: 3]

Boards used for chopping fruit and vegetables can be made from wood or oil-based plastics.

The photograph shows some chopping boards.

Figure for Question 12 — Edexcel A-Level Biology AS

Bacteria can grow on the surfaces of chopping boards.

Explain the conditions that would result in the greatest bacterial growth on the surface of a chopping board.

[Maximum number: 1]

Boards used for chopping fruit and vegetables can be made from wood or oil-based plastics.

The photograph shows some chopping boards.

Figure for Question 13 — Edexcel A-Level Biology AS

The number of bacteria surviving on boards made from different materials was investigated.

Identical bacterial cultures were placed on boards made of pine wood, spruce wood and plastic. The graph shows the number of bacteria surviving after bacteria were placed on the boards and kept in the same conditions.

Table for Question 13 — Edexcel A-Level Biology AS

Suggest one reason for the difference in bacterial survival on the pine chopping board and on the plastic chopping board.
(1)

[Maximum number: 9]

Petri dishes with nutrient agar were used in an investigation of the antimicrobial properties of plant extracts. Bacteria were spread on the surface of the agar to form a lawn. Plant extracts were placed in wells cut in the agar. After incubation, the size of the zone of inhibition is a measure of the antimicrobial effect of the plant extract. The diagram shows a Petri dish after the incubation period.

Figure for Question 14 — Edexcel A-Level Biology AS

(a)

Explain three aseptic techniques that should be used when transferring bacteria from one culture to another. (3)

[ 3 ]

(b)

The technique described was used to investigate the antimicrobial effects of oil A and oil B, extracted from two species of plant. Different bacterial lawns were made using E. coli and B. subtilis.

[ 6 ]

(i)

Explain how the area of the zone of inhibition could be measured accurately.

[ 2 ]

An explanation that includes the following points:

- use of squared paper (1)

- detail of what to do with paper to get area (1)

OR

- measure \{diameter / radius\} \{using callipers / in more than one direction\} (1)

- detail of calculation of area from this (1)

e.g. treatment of part squares do not accept unqualified count squares

accept micrometer and/or graticule accept different angles

e.g. $\pi \mathrm{r}^{2}$

(ii)

The table shows the results from this investigation.

Table for Question (ii) — Edexcel A-Level Biology AS

Determine the effect of these two oils on the growth of these bacteria.

[ 4 ]

An answer that includes the following point:

- a calculation to compare two relevant results between different \{oils / bacteria\} (1)

and any three of the following:

- oil A is a more effective (inhibitor of bacterial growth) than oil B (on both bacteria) (1)

- both oils are more effective (inhibitors of bacterial growth) on B. subtilis (than on E. coli) (1)

- oil B (inhibits only B. subtilis / does not inhibit E.coli) / oil A inhibits both bacteria (1)

- biggest (anti-bacterial) effect is A on B. subtilis / smallest (anti-bacterial) effect is B on E. coli (1)

penalize the idea that the effect is a stimulus to growth once only. e.g. B. subtilis $20.66 \div$ $11.33=1.82 \times$ more inhibited by A than B
oil A has 9.33 greater zone of inhibition than oil B on B. subtilis
oil A affects B. s. 2.4 times more than it affects E. c. or reverse calculation
many other calculations are possible for the mark
accept Z.o.l. bigger for more effective
accept reverse argument
do not piece together, must be clearly stated

[Maximum number: 2]

The five stages of cancer are used to describe the size and spread of a cancer in a human body.

Anticancer drugs have to undergo double-blind trials before they are used to treat patients.

Describe how a placebo is used in a double-blind trial.

[Maximum number: 1]

The common wombat is endemic to Australia and Tasmania.
The photograph shows a common wombat.

Figure for Question 16 — Edexcel A-Level Biology AS

magnification $\times 0.1$

Common wombats mark areas of their habitat to signal to other wombats of the same species that they are living there. These marked areas are called territories.

Common wombats produce cube-shaped faeces. It is thought that these cubes can be stacked to mark territory without rolling away.

State what is meant by the term species.

[Maximum number: 1]

The photograph shows a mother and baby Malayan tapir (Tapirus indicus). They live in the rainforests of southeast Asia. Each gamete of a Malayan tapir contains 26 chromosomes.

Figure for Question 17 — Edexcel A-Level Biology AS

The map shows the change in distribution of the Malayan tapir over the past 20 years.

One difference is that the distribution has reduced due to human activity. Suggest one reason why human activity has caused this change in distribution.

[Maximum number: 2]

Flowering plants produce seeds that can be stored in a seed bank. This is done to conserve the biodiversity of plants.

State what is meant by the term biodiversity.

[Maximum number: 1]

The photograph shows a mother and baby Malayan tapir (Tapirus indicus). They live in the rainforests of southeast Asia. Each gamete of a Malayan tapir contains 26 chromosomes.

Figure for Question 19 — Edexcel A-Level Biology AS

Biodiversity within a species can be measured using genetic diversity. Three melanistic Malayan tapirs have been discovered that have black fur all over their bodies. Melanistic tapirs have two copies of the recessive allele for fur colour and are homozygous.

Scientists wanted to determine the heterozygosity index of the Malayan tapir species. Which equation can be used to calculate the heterozygosity index? □ A □ B C

Table for Question 19 — Edexcel A-Level Biology AS

The only correct answer is A number of heterozygotes ÷ number of individuals in the population
B is not correct because the equation is number of heterozygotes $\div$ number of individuals in the population
C is not correct because the equation is number of heterozygotes ÷ number of individuals in the population
D is not correct because the equation is number of heterozygotes ÷ number of individuals in the population

[Maximum number: 4]

The photograph shows a species of fungus growing on a dead tree in a woodland habitat.

Figure for Question 20 — Edexcel A-Level Biology AS

© www.pqpictures.co.uk / Alamy Stock Photo

Wood contains a high proportion of lignin and cellulose. Fungi can break down molecules in wood by releasing extracellular enzymes.

(a)

A study compared the biodiversity of two woodland habitats. The index of diversity for habitat one was 4.2. The table shows the data obtained from habitat two.

Table for Question (a) — Edexcel A-Level Biology AS

[ 4 ]

(i)

An index of diversity (D) is calculated using the formula:

\mathrm{D}=\frac{\mathrm{N}(\mathrm{~N}-1)}{\sum \mathrm{n}(\mathrm{n}-1)}

Calculate the index of diversity for habitat two. Use the table and the formula to help you.

[ 3 ]

An answer that includes the following points:

- N(N-1) correctly calculated (1)

- $\quad \sum \mathrm{n}(\mathrm{n}-1)$ correctly calculated ( 1 )

- calculation of D for habitat two ( 1 )

Figure for Answer to Question (i) — Edexcel A-Level Biology AS

(3)

Species	Number of individuals (n)	n(n−1)
A	34	1122
B	6	30
C	27	702
D	4	12
E	9	72
F	31	930
G	120	14280

N=231

$\sum n(n-1)=17148$

D=3.098

ALLOW ecf for mp3 if rounded correctly
IGNORE fractions
correct answer on answer line scores 3 marks

(ii)

State which habitat has the higher biodiversity. Give a reason for your answer.

[ 1 ]

[Maximum number: 2]

The common wombat is endemic to Australia and Tasmania.
The photograph shows a common wombat.

Figure for Question 21 — Edexcel A-Level Biology AS

magnification $\times 0.1$

Common wombats dig burrows to live in. They have adaptations to help them to do this successfully.

Describe two anatomical adaptations of a common wombat that help it to dig burrows to live in.

Use the information in the photograph to support your answer.

1

[Maximum number: 2]

The photograph shows a mother and baby Malayan tapir (Tapirus indicus). They live in the rainforests of southeast Asia. Each gamete of a Malayan tapir contains 26 chromosomes.

Figure for Question 22 — Edexcel A-Level Biology AS

Biodiversity within a species can be measured using genetic diversity. Three melanistic Malayan tapirs have been discovered that have black fur all over their bodies. Melanistic tapirs have two copies of the recessive allele for fur colour and are homozygous.

Explain how scientists could determine if a change in the frequency of the recessive allele was occurring over time.

An explanation that makes reference to two of the following points:

- count the number of tapirs and {melanistic / all black} tapirs in the population (1)

- use the Hardy-Weinberg equation to calculate the recessive allele frequency (1)

- compare to previous recessive allele frequency to see if it has changed (1)

ACCEPT determine the number of {melanistic / all black} tapirs and the population size

ACCEPT correct Hardy-Weinberg equation

ACCEPT calculate {for each generation / at two(+) different time periods} and see if there is a change (over time) IGNORE see if there is a change in frequency

IGNORE q ${ }^{2}$

[Maximum number: 3]

The photograph shows a mother and baby Malayan tapir (Tapirus indicus). They live in the rainforests of southeast Asia. Each gamete of a Malayan tapir contains 26 chromosomes.

Figure for Question 23 — Edexcel A-Level Biology AS

The map shows the change in distribution of the Malayan tapir over the past 20 years.

A study suggested that the genetic diversity of the Malayan tapirs has decreased due to populations being separated from each other.

Explain how a captive breeding programme could maintain the genetic diversity of Malayan tapir populations.

Edexcel A-Level Biology AS 4 Plant Structure and Function Biodiversity and Conservation Questions

Exam points

Covered syllabus points

Covered syllabus points

Question 1

Question 2

Question (a)

Question (i)

Question (ii)

Question (b)

Question (i)

Question (ii)

Question 3

Question (a)

Question (i)

Question (ii)

Question 4

Question 5

Question 6

Question 7

Question 8

Question (a)

Question (b)

Question (c)

Question 9

Question 10

Question (a)

Question (b)

Question (i)

Question 11

Question (a)

Question (i)

Question (ii)

Question 12

Question 13

Question 14

Question (a)

Question (b)

Question (i)

Question (ii)

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

Question (a)

Question (i)

Question (ii)

Question 21

Question 22

Question 23