Holy Cross High School

Biology

Past Paper Questions

Unit 3 – Life on Earth

Biodiversity and the distribution of life

1. The total variety of all things on Earth is described asa. an ecosystem

b. biodiversityc. a communityd. random assortment.

2. A Treecreeper is a bird which feeds on small insects on the bark of the trees during the day.What is correct description of the Treecreepers’s niche?

a. The place where it livesb. The insects on which it feedsc. The plants and animals in the woodland environment d. Its role within the woodland ecosystem.

3. Which on the following statements about a woodland describes a community? a) All Oak trees b) All the plants c) All the oak trees and blackbirdsd) All the plants and animals

4. Marsh marigold is a waterside plant which grows beside burns.

The abundance of marsh marigolds was estimated in five sampling areas beside a burn in the Scottish borders, Average values of three abiotic factors were also calculated for each area.The results are shown in the table below

a) Name one abiotic factor which does not affect the abundance of marsh marigolds.

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b) The soil pH for each sampling area was measured using a pH meter with a probe which was pushed into the soil to obtain each reading.

i. Identify a possible source of error in measuring a named abiotic factor and suggest how to minimise it.

ii. How was the measurement of the abiotic factors in this survey carried out to reduce the effect of a typical result?

5. Read the passage below and use the information to answer the questions which follow. (Adapted from Hostile Habitats, Scottish Mountaineering Trust, 2006).

As you climb a mountain or hill, the vegetation gradually changes. In Scotland, trees and tall grasses in the glens are replaced on the mountain tops by lichens and dwarf mosses less than a centimetre high. The treeline is the maximum altitude at which trees can grow. Scottish hills have relatively little tree cover and so the treeline is not always obvious but it does form a real ecological boundary. If trees had not been cleared by humans in past centuries, the slopes below the treeline would be covered in forest. Low growing vegetation is dominant on the higher slopes.

The factors which produce the treeline are not clearly understood but the average temperature during the growing season seems to be important. Under colder conditions, trees are at a disadvantage

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compared to low growing, denser vegetation. The growing tips of trees are fully exposed to high winds which cause physical damage and slow down growth of shoots by drying them out. High winds in wet conditions cause wind chill which can further damage shoots. In the case of low growing plants, these effects are reduced as their growing shoots are protected by the surrounding vegetation.

The treeline in Scotland is generally lower than in other countries a similar distance from the equator. The exact height of the treeline varies across Scotland. The wet and windy conditions in the west of Scotland produce a treeline between 200 m and 450 m above sea level. In the east of Scotland, the treeline is between 500 m and 650 m above sea level. Other types of vegetation show similar effects, with mountain plants being found at lower levels on the west coast.

a) Give two types of plant you might expect to find growing on mountain tops in Scotland. lichens and dwarf mosses/evergreens

b) Most hills in Scotland do not have woodland present up to the potential; treeline. Why is this? Max altitude at which trees can grow

c) According to the passage, what factor might be important in determining how high up a hill trees can grow? Average temperature

d) What two factors are needed to produce wind-chill? High winds and wet conditions

The passage states that, “low growing vegetation is dominant on the higher slope”. What advantage does this type of vegetation have which allows it to grow at higher altitudes than trees? growing shoots are protected by the surrounding vegetation.e) In summer. Red deer migrate to graze above the treeline. In which

part of Scotland would they have to go higher to do this? East of Scotland

6. An ecosystem has several components.

Copy and complete the table below to identify the terms used and their definitions.

Term DefinitionProducer A green plant that makes its own food.Carnivore eats other animals

Community All the plants, animals and microorganisms living together in an ecosystem

Population All the animals or plants of a single species living in an area.

Habitat place where an organism lives

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Energy in ecosystems

1. The table below shows the relationship between planting density and the mass of seed harvested for a trial cereal crop.

Planting density (number of plants per square metre)

Mass of seed harvested

(grammes per square metre)

4 218 7715 10532 77128 21

The reason a low mass of seed was harvested when the planting density was 128 plants per square metre was

a) less disease at high planting densities b) more nutrients available c) more competition for light and nutrients d) less space for weeds

2. Two groups of the seeds of genetically tall plants were grown under different conditions. Group one’s seeds were grown in high light intensity and high nutrient levels. Group two’s seeds were grown in low light intensity and low nutrient levels.All plants in group one were taller than those in group two.

The effect of the different conditions on the phenotype is due to

a) natural selectionb) biodiversityc) environmental impactd) polygenic inheritance.

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3. The diagram below shows the number of organisms at each level in the pyramid of numbers.

How many organisms are consumers?

a) 2b) 82c) 6000d) 6082

4. The diagram below shows the feeding relationships of some of the organisms found in a fresh water loch.

Which population of organisms in this food web would have the smallest biomass?

a) Pikeb) Troutc) Microscopic animals d) Microscopic plants

5. The diagram below shows part of a food web in an oak woodland.

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The use of insecticides in a nearby field resulted in the death of most aphids and caterpillars.

Which line in the table identifies the effect on the numbers of slugs and carnivorous insects? B

6. A study has shown that Scotland’s river otter population is increasing after falling sharply over the last 40 years.

Otters live along the banks of rivers, usually in reeds and gaps between tree roots. Fish are their main food.

a) What term is used for the place where otters live? Habitatb) What disadvantage might otters have if reeds are removed from riverbanks? At risk of predatorsc) Mink are North American animals introduced into Scotland. They feed on fish and live in riverbanks.What effect would the mink have on otter numbers? Explain your answer.Decrease due to competition for resources

7. The diagram below represents a food web from a Scottish river ecosystem.

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a) Copy the table below and decide if each of the following statements about this food web is TRUE or FALSE, and tick () the appropriate box. If the statement is FALSE, write the correct word in the correction box to replace the word underlined in the statement.

Statement True False CorrectionThe stone loaches are the predators of the brown trout.

x prey

There are three producers in this food web.

x two

The caddis fly larvae are herbivores.

x

b) i) Complete the food chain below with four organisms from this food web.

Water weed, water snails, stone loaches, brown trout, heron

ii) What do the arrows in the food chain represent? Direction of energy flow

c) A pyramid of biomass shows the mass of living organisms at each level. Explain why the heron has the lowest biomass in this food web.

energy lost as it passes through the food chain heron has least energy available to build tissues or

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fewer heron than any other organism (must be comparative)

8. The diagram below represents part of the nitrogen cycle.

a)i) Use letters from the diagram to identify the following.Each letter may be used once, more than once or not at all. B/C&D/G

ii) Which type of organism is responsible for process D? Nitrifying bacteriab) In an investigation, wild rabbits were found to eat an average of 600g of grass per day. This grass contains 450g of water. The dry weight of the grass contains 20% protein.

Calculate how much protein a rabbit eats each day. 30

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9. a) Root nodules contain bacteria which are involved in the nitrogen cycle. Bean plants were grown in pots of sand containing different masses of nitrogen fertiliser. After ten weeks, the root nodules were removed, washed and weighed. The average mass of root nodules per plant was calculated. The results are shown in the graph below.

i) Using data from the graph, describe the relationship between the mass of nitrogen fertiliser and the average mass of root nodules per plant. As mass of nitrogen fertiliser increasers, the average mass of root nodules per plant decreases.

ii) Predict the average mass of root nodules per plant if 7g of nitrogen fertiliser were added. 0.1g

b) The recycling of nitrogen in ecosystems depends on the action of bacteria.

Choose one type of bacteria from the list and describe its role in the nitrogen cycle.

Nitrifying bacteria - convert the ammonia into nitrites then nitrates Denitrifying bacteria - change soil nitrates into nitrogen gas Root nodule bacteria - fix nitrogen into nitrates

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10 a) The diagram below shows part of a woodland food web.

Use the words increase,

decrease or stay the same to describe the effect on the populations of greenflies and stoats if all the mice were killed by a disease. Give a reason for your answer.

i) Effect on greenfly population – decrease as ladybirds would increase and eat more greenflies

ii) Effect on stoat population - decrease as losing only source of food

11. a) A food chain is shown below along with three pyramids of numbers.

Identify the pyramid which represents the food chain shown. L

b) This food chain can also be represented by a pyramid of biomass. State the meaning of the term “pyramid of biomass”.

A pyramid of biomass is a diagram showing the mass (weight) of organisms present at each level of the food chain

c) i) Calculations were made of estimate the energy content of a food chain involving three species.

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Two of these values are given in the table below. Complete the table by calculating the missing energy value. 9700

ii) State one way in which energy may be lost between stages in a food chain.

1. Undigested materials – parts left uneaten or expelled as waste2. Movement – most energy gained by an organism is used to power movement3. Heat – organisms use energy for keeping warm

Sampling techniques and measurement of abiotic & biotic factors

1. Which one of the following graphs shows the effects of competition for the same food between a successful species and an unsuccessful species? C

2. Students used a quadrat to estimate the number of buttercups in a field. They threw the quadrat randomly three times in the area.In order to improve the reliability of their results they could have

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a) asked another group of students to check that they had counted correctly.

b) thrown the quadrat ten times instead of threec) only thrown the quadrat when conditions were at an optimum d) used a smaller quadrat for each of their samples.

3. Three groups of students used quadrats to carry out a survey in the distribution of mussels on different areas of a shore.

Each quadrat measured 50cm x 50cm. (Four quadrats = 1m2).

The positions of the quadrats and the number of mussels found are shown below for each group.

a) Copy and complete the following table with the results from the area of group C.

Group Average number of mussels per quadrat

Estimated number of mussels per m2

A 11 44B 16 64

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C 10 40

b) Which group has made an error in their sampling technique which makes their results less reliable than the other groups? State the error this group has made and describe an improvement which would increase the reliability of their results. A only sampled twice and should sample more times (ideally all groups are the same)

4. The diagram shows the results of a survey of seaweeds on a rocky Scottish shore. Starting at the highest tide level, square quadrats were placed every 5m in a line down the shore. Four species of seaweed were rated as absent, scarce or abundant in each quadrat.

a) How many species of seaweed were found in quadrat number 9?2

b) How many of the quadrats contained more than one species of seaweed? 7

c) Which species of seaweed spends less time covered by water?

Eggwrack

d) What percentage of all the quadrats included egg wrack? 60%

e) Suggest one abiotic factor that might affect the distribution of seaweed species on the shore. Light intensity/temperature

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f) Suggest one possible source of error in the sampling procedure and explain how it might be minimised. Only attempted once so repeat more times

5. Two groups of pupils set pitfall traps in the school gardens to sample invertebrates living there. All traps were left for the same length of time. The results are shown in the following tables.

Group A

Pitfall trap

number

Number of each type of invertebrate caughtspider beetle snail earthwor

mwoodlou

se1 2 1 2 0 12 3 2 1 0 1

Group B

Pitfall trap

number

Number of each type of invertebrate caughtspider beetle snail earthwor

mwoodlou

se1 2 3 2 1 12 2 0 3 1 23 0 2 1 1 14 3 2 1 0 15 3 1 1 2 1

a) How many types of invertebrates did group A find? 4

b) Calculate the average number of spiders found in group B’s traps. 2

c) Explain why conclusions made by group B from their results would be more reliable than conclusions made by group A. Group B repeated more times.

d) Give one precaution which must be taken when setting up a pitfall trap, or other named sampling technique, and explain the reason for it.

Birds may eat trapped animals/animals might eat each other so disguise the opening and check regularly.

e) The diagrams below show the invertebrates collected by the pupils. They are not drawn to scale.

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Copy and complete the following paired statement key.

1 Legs ......................................................................................... Go to 2

No legs .......................................................................3.......... Go to

2 12 legs or more ........................................................................... woodlouse

Fewer than 12 legs ...................................................................... Go to 3

3 spots on body ................................................................................ Beetle

No spots on body ...................Spider........................................................

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Shell .................................................................................................. Snail

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f) Give three features of the beetle mentioned in the key.

Legs, fewer than 12 legs and spots on body.

6. A comparison was made between the types of invertebrate animals living on the branches and leaves on an oak tree with those living on a beech tree. Samples were collected as shown below.

EarthwormNo shell 3

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a) Give two variables that should be kept constant to make the comparison valid when using this technique. Same number of shakes/same height or distance/same stick/same size of sheet.

b) The samples collected were not representative of all the invertebrates living on the trees. Suggest a reason for this. Some may have been higher up in the tree or not near the area the technique was being used.

c) Measurement of abiotic factors such as light intensity may be recorded at the same time as sampling. Identify a possible source of error for a named measurement technique and explain how it might be minimised.

Light = The observer may stand in the way of the light and cast a shadow on the meter so stand to one side

Moisture = Moisture from a previous measurement may be left on the probe and affect the next reading so wipe probe clean.

Temperature = probe not inserted deep enough so ensure probe is pushed into soil to half its depth.

pH = reading may be contaminated from previous so wipe it clean.

d) An investigation was carried out into the effect of light intensity on the distribution of a plant species. At eight different measurement points in the garden, the average light intensity was measured and the percentage ground cover of the plant was recorded. The results are shown below.

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i) What is the light intensity in the garden when the ground cover of the plant is 100%? 2000lux

ii) What was the percentage ground cover of the plant when the light intensity was 750 lux? 65

iii) What is the relationship between light intensity and percentage ground cover of the plant? As ground cover increases, light intensity also increases.

iv) Explain how light intensity affects the distribution of the plants in the garden. More plants distributed in areas of higher light intensity.

Adaptation, natural selection and the evolution of a species

1. The diagram below represents a population of animals.

The following diagrams show the stages of speciation occurring from this population.

The correct order of the stages of speciation is

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a) Z,W,X,Yb) Z,X,W,Yc) Y,X,Z,Wd) Y,Z,X,W

2. The table below compares the rate of extinction of mammal species over two different time periods.

The ratio of extinction rates between 1900-2000 compared to 1500-1900 is

a) 1:20b) 1:2c) 2:1d) 20:1

3. A choice chamber was used to investigate the effect of humidity on the behaviour of woodlice, as shown below.

Which line in the table below describes the most appropriate set up for this investigation? D

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4. The diagrams below give some information about three species of Darwin’s Finches which live on the Galapagos Islands.

a) Using evidence from the diagrams, explain why these finch species occupy different niches.

beak shapes/sizes/structures

Different food sources/types

b) Some areas on the island have a thin layer of soil and low rainfall.

Describe two adaptations which plants growing in these areas will have to help them survive.

Spines instead of leaves/smaller leaves to reduce water loss/ shallow root systems that take up nutrients in the top layer of soil

5. a) The Cichlid fish below are all found in Lake Malawi in Africa.

i) Using the information shown, identify the feature which enables the fish to have different diets. Shape of mouth/head

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ii) Predict two species of cichlid which would be in competition with each other if there was a shortage of fish eggs. Give a reason for your answer. B&D because they both eat small fish.

b) State the term which describes the role that an organism, such as the cichlid, plays within its community. Niche

c) Fresh water environments, such as Lake Malawi, can be affected by human activities. The overuse of fertilisers can impact on the organisms living in these environments.

Rearrange the following statements o show how this might occur. 3,1,5,4,2

1. Chemicals leach into water 2. Fish die3. Overuse of fertilisers 4. Oxygen levels decrease 5. Algal bloom develops

Place the statement number in the correct box.

d) A fresh water environment is an example of an ecosystem. Describe what is meant by the term ecosystem.

The balanced interaction between the members of a community and their physical habitat/ natural biological unit made up of living and non-living parts

Human impact on the environment

1. Swans and cygnets (young swans) live on the River Ayr. Foxes in the area kill and eat cygnets.

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a) Copy and complete each sentence underlining the correct word in each set of brackets.

Cygnets are the of foxes.

The foxes are consumers.

b) Fifty cygnets were counted in 2008. By 2009, 18 of these cygnets had been killed by foxes. What percentage of the cygnets survived to 2009?64%

c) Dead adult swans were found throughout the year. It was discovered that the use of lead weights by anglers was poisoning the swans. Other animals in the river were also affected by the lead.

Suggest the effect of the lead on the biodiversity of a river ecosystem, and explain your answer.

Decrease – poisoning range species within the ecosystem, reducing the amount/variety of species.

d) State another type of pollution which may affect biodiversity in the river.

Water pollution/air pollution

2. The table shows the mass of some of the main air pollutants produced in Britain in one year.

Pollutant Mass produced (tonnes per year)Sulphur dioxide 4000Dust and grit 1500Carbon monoxide 6000Smoke 1000Others 500TOTAL

preypredators

secondaryprimary 1

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a) Copy and complete the table by entering the total mass of pollutants in the space provided. 13000

b) The pie chart below shows the information from the table.

i. Which letter represents the pollution due to dust and grit? A

ii. Identify the pollutants represented by segments C and D on the chart. Carbon monoxide and smoke

3. The graphs below show the oxygen concentrations upstream and downstream from the outflow pipes of two different sewage works, A and B. The two sewage works receive equal quantities of sewage and the two rivers are of equal size and speed.

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a) What is the oxygen concentration of the water upstream from sewage works A? 2.8cm3 per l

b) Calculate the percentage of oxygen lost from the water between the outflow of sewage works B and point X. 50%

c) Copy and complete the following sentence to describe the change in oxygen concentration which takes place downstream from both sewage works.

As the distance downstream from the sewage works increases, the oxygen concentration .............decreases................................... and then .......increases................................ .

d) Which sewage works is more efficient at removing waste material from the sewage? Give a reason for your answer.

B – oxygen levels don’t decrease as much as sewage works A

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4. Microorganisms living in water use dissolved oxygen for respiration. The mass of oxygen they use is called the Biochemical Oxygen Demand (BOD). The table below shows the BOD of a river and the concentration of solid material carried by the river during five months of the year.

Month Concentration of solid material (mg/l)

BOD (mg/l)

January 6.75 1.0March 7.25 1.2May 10.75 1.9September 5.50 0.5November 9.00 1.5

a) Use the information in the table to copy and complete the bar chart below for January and November. 1

b) Describe the relationship between the concentration of solid material in the river water and the BOD. As concentration of solid material increases, BOD also increases.

c) After heavy rains in December, the concentration of solid material in the water was found to be 10.0mg/l. What would be the expected BOD for this sample? Select from 7.5mg/l; 5.0mg/l; 1.75mg/l or 1.25mg/l.

5. How Europe’s bird numbers collapsed

The number of farmland birds in Europe has decreased dramatically in recent years. A study estimated that the total bird population has dropped from 600 million to 300 million between 1980 and 2009.

It is suggested that changes in farming policies may be largely responsible for this reduction. It has been claimed that intensive farming methods have killed many of the insects eaten by bird species.

The effect on the populations of some bird species is shown in the table below.

i) Explain why the population decrease was expressed as a percentage rather than a decrease in number. Varying range of numbers so percentage gives a better representation of the decrease.

ii) Using information from the passage and the table, calculate the percentage of meadow pipits in the total bird population in 2009. 4.3%

iii) Which two species of birds were least affected between 1980 and 2009? Starling and yellow wagtail

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b) One of the advantages of intensive farming is to increase the yield of food crops which can make them more affordable. It also has a number of disadvantages as shown in the list below.

List

Forests are destroyed to create large open fields and this could lead to soil erosion

The natural habitats of wild animals are affected Loss of biodiversity Use of fertilisers can alter the biology of rivers and lochs Pesticides sprayed on crops not only destroy pests but also kill

beneficial insects Toxic effects from pesticides may affect human beings and other

organisms when they consume the food crops.

Biological control and GM crops are methods used in farming.

Choose one of these methods and explain how it is used to overcome some of the disadvantages of intensive farming listed above.

Biological control = A more natural way of protecting crops from pest species involves releasing a natural predator into the crop growing area. The predator will kill and eat the pest (prey) and as a result the number of pests will drop leaving beneficial insects behind and it wont have toxic effects on humans/other organisms when consumed.

GM crops = Another way to increase plant yield without the use of fertilisers is to use genetically modified crops. Genetically modified crop plants have received genes from other organisms in order improve their characteristics. Scientists have added genes from bacteria into the crop plants maize and potatoes that make them toxic to insects. This reduces the need to use large quantities of insecticides.

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