B1 and b2 easter revision booklet by Isaac Newton Academy

Name: _______________________________________________

Easter IL B1 and B2 Date:

Total marks available: 120 Total marks achieved: ______

Questions Q1.

Classification

(a) All the organisms in the diagram belong to one Kingdom.

(i) Which Kingdom do these organisms belong to? Place a cross (

) in the box next to your answer. (1)

A B C D

Animalia Fungi Protoctista Prokaryotes

(ii) In which structure are the chromosomes of these organisms found? Place a cross ( ) in the box next to your answer. (1) A B C D

cilia chloroplast flagellum nucleus

(iii) Suggest one reason why both Euglena and Chlamydomonas could be placed into the Kingdom Plantae. (1) ............................................................................................................................................. ............................................................................................................................................. (b) (i) Euglena is unusual because it is both heterotrophic and autotrophic.

Explain how this helps Euglena to survive. (3) .......................................................................................................................................................................

....................................................................................................................................................................... (ii) A scientist discovered a new species of Euglena in boiling acidic mud in Costa Rica. Explain how this discovery could be validated by the scientific community. (2) .......................................................................................................................................................................

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

(Total for question = 8 marks)

Q2.

The peppered moth (Biston betularia) exists in dark and light forms.

(i) Complete the sentence by putting a cross ( ) in the box next to your answer. Characteristics such as colour are coded for by alleles. An allele is (1) A B C D

a single chromosome a single gene an alternative form of the same chromosome an alternative form of the same gene

(ii) The allele for the dark colour is B and is dominant. The allele for the light colour is b and is recessive. Complete the table to show all possible genotypes of dark moths. (2) possible genotypes of dark moths

(iii) Complete the Punnett square for a cross between a moth heterozygous for colour and a moth homozygous recessive for light colour. (2)

(iv) Give the ratio of light to dark moths in the Punnett square in (a)(iii). (1) ..............................................................................................................................................

Q3.

Cystic fibrosis is a genetic disorder caused by recessive alleles.

The diagram shows the inheritance of cystic fibrosis in a family.

(i) State the number of offspring in generation III who will have the disorder cystic fibrosis. (1) .............................................................................................................................................. (ii) Complete the sentence by putting a cross ( In generation III, individual 3 is

) in the box next to your answer. (1)

A B C D

a carrier of the cystic fibrosis allele heterozygous for cystic fibrosis homozygous dominant for cystic fibrosis homozygous recessive for cystic fibrosis

(iii) Explain why both individuals in generation II must be heterozygous for cystic fibrosis. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................

Q4. Fetal alcohol syndrome occurs when a pregnant woman drinks large quantities of alcohol. The diagram shows the development of the embryo and fetus during its time in the uterus. The bars show the time period during which fetal alcohol syndrome can cause an abnormality in a specific body part. The darker the bar, the more likely an abnormality will occur in that body part.

(a) (i) Complete the sentence by putting a cross ( ) in the box next to your answer. The body part most likely to be affected by fetal alcohol syndrome throughout pregnancy is the (1) A B C D

central nervous system heart arms eyes

(ii) State the period of time when a defect in the development of the legs is most likely to occur. (1) .............................................................................................................................................. (b) (i) Alcohol is a drug. Define the term drug. (2) ....................................................................................................................................................................... ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ (ii) Explain why alcohol is classed as a depressant. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................

........................................................................................................................................................................ ........................................................................................................................................................................ (c) (i) Describe a long-term effect of alcohol abuse. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ (ii) Discuss the ethics of allowing alcoholics to have an organ transplant. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ (Total for Question is 10 marks)

Q5.

The graph shows the body temperature of 60 people.

(i) Complete the sentence by putting a cross ( The range in body temperature is

) in the box next to your answer. (1)

A B C D

0.1 1.1 11.0 11.1

(ii) State the type of variation, shown in the graph, that results in a normal distribution curve. (1) .............................................................................................................................................. (iii) Calculate the percentage of people with a body temperature of 37.5 째C. (2) ..............................................................................................................................................

Q6.

Blood glucose regulation

(a) The graph shows the concentration of glucose in the blood of two people and how this changes over a two-hour period.

(i) Calculate the difference in the blood glucose concentration between person A and person B at 90 minutes. (2) answer = ............................................................................. mmol/dm 3 (ii) Using the information from the graph, describe the change in blood glucose concentration for person B during this two-hour period. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ (iii) State which hormone a type 1 diabetic, such as person A, would use to control their blood glucose concentration. (1) .............................................................................................................................................. (b) (i) Complete the sentence by putting a cross ( Excess glucose is converted into glycogen in the

) in the box next to your answer. (1)

A B C D

brain kidney liver pancreas

(ii) Type 2 diabetics also have problems with blood glucose regulation.

Explain how type 2 diabetics control their blood glucose concentration. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ Q7.

Gareth carried out an investigation to see the effect of sunlight on grass shoots.

He set up four grass shoots.

Results of the experiment after 48 hours: grass shoot 1 grew straight upwards grass shoot 2 grew and curved towards the right grass shoot 3 did not grow grass shoot 4 grew and curved towards the left (i) Which grass shoot was the control in this experiment? (1) Put a cross ( A B C D

) in the box next to your answer.

grass shoot 1 grass shoot 2 grass shoot 3 grass shoot 4

(ii) The growth of the grass shoots towards the direction of the light is called phototropism. Give the name of the hormone that causes this reaction in grass shoot tips. (1) ..............................................................................................................................................

(iii) Explain how this experiment provides evidence that the hormone causing phototropism is found in the shoot tip. (2) .......................................................................................................................................................................

....................................................................................................................................................................... Q8.

The food chain shows the energy transferred between organisms.

(i) The oak tree is the producer in the food chain. Complete the sentence by putting a cross ( The oak tree obtains energy

) in the box next to your answer. (1)

autotrophically

heterotrophically

parasitically

saprophytically

(ii) The energy available in the oak tree that could be transferred to the caterpillars was 97 000. Calculate the percentage loss of energy between the oak tree and the caterpillars. (3)

........................................................... % (iii) Suggest how energy is lost between trophic levels in this food chain. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ Q9.

The diagram shows the processes involved in the carbon cycle. Each process is numbered. atmospheric carbon dioxide

(i) What is the name of process 1? Put a cross ( ) in the box next to your answer. (1) A B C D

decomposition denitrification photosynthesis respiration

(ii) Describe the numbered processes that return carbon dioxide back into the atmosphere. (3) .......................................................................................................................................................................

........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ Q11.

Mutations can occur in genes.

Mutations can cause genetic disorders in humans. Phenylketonuria (PKU) is a genetic disorder caused by a gene mutation. People with PKU produce an inactive enzyme. The normal base sequence and the mutated base sequence which can cause PKU are shown below. normal base sequence ............ C T C G G C C C T............ mutated base sequence ............ C T T G G C C C T............ (i) Describe how the changes that have occurred in the mutated base sequence produce an inactive enzyme. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ *(ii) Explain how the mutated base sequence will result in an inactive enzyme being produced during protein synthesis. (6) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................

DNA

The two strands of a DNA molecule are linked together by paired bases.

(a) (i) Draw one straight line from each base to its complementary base. (2)

(ii) Complete the sentence by putting a cross (

) in the box next to your answer.

The base pairs in a DNA molecule are held together by (1) A B C D

weak hydrogen bonds strong hydrogen bonds weak ionic bonds strong ionic bonds

(b) DNA can be extracted from onion cells. Explain why it is important to crush the onion cells gently at the start of the process. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ (c) Organisms can be genetically engineered to make them more useful to humans. Suggest how wheat could be genetically engineered to allow it to grow in wet, marshy land. (3) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................

* The diagram shows some of the stages that occur in the formation of a human fetus.

Using the diagram and your own knowledge, describe the processes that take place in the formation of the fetus from a sperm cell and an egg cell. (6) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................

Q14.

Discuss the advantages and disadvantages of cloning organisms. (3)

Iguanas are reptiles that usually have green or yellow skin.

Some iguanas found on the Galapagos Islands have a pink skin.

The colour of the pink iguana is the result of a gene mutation. (i) The change in the DNA sequence that causes the pink skin in iguanas is a result of four amino acids being altered. How many bases code for four amino acids? (1) ........................................................................................................................................................................ ........................................................................................................................................................................ (ii) DNA analysis suggests that the pink iguanas split from the more common yellow iguana population 5.7 million years ago. Give one reason why the fossil record has not been able to support this date. (1) ........................................................................................................................................................................ ........................................................................................................................................................................ Q16.

Plants and carbon dioxide

This headline appeared in a newspaper:

Scientists are worried that the destruction of tropical rainforests will result in much higher levels of carbon dioxide in the atmosphere.

(a) Put a cross ( ) in the box next to your answer. What process removes carbon dioxide from the atmosphere? (1) A B C D

respiration transpiration photosynthesis osmosis

(b) Suggest why the destruction of rainforests may result in higher levels of carbon dioxide in the atmosphere. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ (c) Explain one adaptation of a leaf which enables it to carry out gas exchange. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................

(d) A cleared rainforest is used to grow crops. (i) Diego used a half metre quadrat to investigate the number of weeds in a field next to the rainforest. Each side of the half metre quadrat is half a metre long. He randomly placed the half metre quadrat and found an average of seven weeds in each quadrat. The field had dimensions of 100 m by 180 m. Use the information to calculate an estimate of the number of weeds in the field. (2) .................................................................................. weeds in the field (ii) Describe how Diego could improve the quality of the data in his investigation. (3) ........................................................................................................................................................................

Heart disease can significantly reduce cardiac output.

(i) Complete the sentence by putting a cross ( ) in the box next to your answer. Cardiac output is the volume of blood leaving the (1) A B C D

atrium every heart beat atrium every minute ventricle every heart beat ventricle every minute

*(ii) A reduced cardiac output would affect the performance of an athlete. Explain the effects that a reduced cardiac output would have on the muscle cells of an athlete. (6) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ Q18.

Fossils can provide evidence for evolution.

Explain why the fossil record is incomplete. (2) ........................................................................................................................................................................ ........................................................................................................................................................................

Q19.

A healthy digestive system

The diagram shows the digestive system of a human.

(a) Describe the role of the mouth in digestion. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ (b) Villi are structures in the small intestine. (i) Which one of the statements about villi is true? Place a cross ( ) in the box next to your answer. (1) A B C D

Glucose is the only substance absorbed by villi Three types of enzyme are absorbed by villi The capillary network in the villi have a large surface area The walls of the villi are thicker to absorb more food

(ii) Coeliac disease can cause a loss of microvilli. The table shows how the structure of villi affects the surface area of the small intestine.

A person with coeliac disease has no microvilli in their small intestine. Explain why this person would find it hard to exercise. Use information from the table to help you. (3) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................

(c) Fibre in food is not digested. Fibre makes up most of the solid material in the contents of the small intestine. The recommended daily allowance (RDA) for fibre is between 18g and 30g. Suggest why the muscles in the intestines of someone who eats much less fibre per day than the RDA may have trouble moving food through the small intestine. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ (d) Describe how probiotics containing Bifidobacteria are thought to improve the health of the digestive

system. (2) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ (Total for question = 10 marks) Q20. Celiac disease can destroy the villi that line the small intestine. Explain how this will affect a person with celiac disease. (4) ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................ ........................................................................................................................................................................

Easter Holiday IL B1 and B2 Mark Scheme Q1.

Q2.

Questio n Number (i)

Answer

Acceptable answers

Mark

D Answer

Acceptable answers

(1) Mark

Questio n Number (ii)

Accept any two of the genotypes in any order Answer

Acceptable answers

(2) Mark

1 mark for correct parental gametes 1 mark for correct offspring Answer

Acceptable answers

(2) Mark

2:2

e.c.f

(1)

Answer

Acceptable answers

Mark

2 / two Answer

(offspring) 2 and 3 Acceptable answers

(1) Mark

D Answer

Acceptable answers

(1) Mark

An explanation linking two of the following points: • two of the offspring from generation II had CF (1) • the children with cystic fibrosis must have inherited 1 recessive allele from each parent / children must have 2 recessive alleles (1) • both parents must have 1 recessive allele / be carriers of the CF allele (1)

ORA if homozygous dominant then no CF offspring Ignore: references to genes ORA if homozygous recessive offspring would have CF

(2)

Questio n Number (iii)

Questio n Number (iv) Q3. Question Number (i) Question Number (ii) Question Number (iii)

Q4. Answer a(i) a(ii) b (i)

b(ii)

c(i)

c(ii)

A – central nervous system 4 – 7 weeks A definition including any two of the following: • a chemical substance (1) • has an effect on the body / nervous system / brain (1) • causing psychological / physiological / behavioural changes (1) An explanation including two of the following: • increases reaction times / slows down impulses / reactions(1) • slows down the activity of the brain / nervous system (1) • acts on neurotransmission /at the synapse (1) A description linking the following points: • addiction / alcoholism (1) • liver / brain /kidney damage (1) • cirrhosis / cancer (1) A suggestion linking two of the following points: • alcoholics have caused their liver to fail by their addiction (1) • if alcoholics continue to drink, the organ could be damaged (1) • other people may deserve the liver transplant more (1) • addiction is an illness(1) • everybody has a right to life (1)

Acceptable answers

Mark (1)

Accept 4 ½ - 7 ½ 4 – 7 ½ 4½ - 7 causing changes in behaviour / addiction

(1)

(2)

(2) accept – other organ damage related to alcohol abuse but ignore lung damage (2)

alcoholics damage their own liver / people choose to be alcoholics it is not their fault they are addicted alcoholics may die if they do not get a transplant

(2)

Q5. Answer (i) (ii)

B – 1.1 continuous (data / variation) 18 ⁄60 (1) 0.3 × 100 = 30(%) (1) Or 0.33 × 100 = 33(%) (1)

(iii)

Acceptable answers

Mark (1) (1)

correct answer 2 marks (2)

Q6. Question Number (a)(i) Question Number (a)(ii)

Question Number (a)(iii) Question Number (b)(i) Question Number (b)(ii)

Answer

Acceptable answers

Mark

correct readings from graph (1) 12 – 5 correct answer (1) = 7 (mmol/dm3) Answer

Acceptable answers

(2) Mark

A description including two of the following points • increases from 0 minutes to 60 minutes / peaks at 60 minutes • decrease between 60 and 90 minutes • increases between 90 and 120 minutes • some creditable data manipulation to show an increase/decrease between two time points Answer Acceptable answers

(2) Mark

insulin Answer

Acceptable answers

(1) Mark

C Answer

Acceptable answers

(1) Mark

An explanation linking of the following points in a logical order • controlled through diet so glucose intake is reduced (1) • controlled through physical activity /exercise so excess glucose is used (1)

(2)

Q7. Question number (i) Question number (ii) Question number (iii)

Q8.

Answer

Mark

A Answer

(1) Mark

auxin Answer

(1) Mark

an explanation linking the following: grass shoot 3 has the top covered and does not show any phototropism (1) (so) the hormone must be in the tip of the shoot (1)

Acceptable answers

(2)

Q9. Answer (i) (ii)

Acceptable answers

C photosynthesis A description of the processes that return carbon dioxide to the atmosphere including • respiration in animals / respiration from arrow 2 (1) • respiration in plants / respiration from arrow 5 (1) • decomposition /respiration by microorganisms / decomposition /respiration arrow 3 (1)

Mark (1)

accept trees combusting/burning releasing CO2 ignore references to arrow 1 returning carbon dioxide to the atmosphere / photosynthesis / references to arrow 4 (3)

Q10. Question number *QWC

Indicative content

Level 1

0 1-2

3-4

5-6

Mark

an explanation of the process referring to: • named (6) mineral nitrates/phosphates/potassium/magnesium ions • a description to include the uses of these minerals in plant growth • magnesium for chlorophyll production • phosphates for root and shoot growth. • how decomposers break down dead animals and plants and excretory products • how nitrifying (soil) bacteria convert ammonia to nitrates • how denitrifying bacteria convert nitrates to nitrogen gas • the importance of lightning/fertilisers. no rewardable material • limited explanation of the steps involved in the recycling of nitrogen • many of the steps will be missing or in an incorrect order • limited understanding evident of how the nitrogen cycle is a complete cycle of events • reference to soil bacteria/decomposers will be minimal or omitted • communicates ideas using simple language and some scientific terminology. Spelling, punctuation and grammar are used with limited accuracy • some explanation of the steps involved in the recycling of nitrogen • some of the steps will be missing or in an incorrect order • some understanding of how the nitrogen cycle is a complete cycle of events • some appropriate reference to soil bacteria/decomposers • communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately. Spelling, punctuation and grammar are used with some accuracy • developed explanation of the key steps involved in the recycling of nitrogen • most of the steps will be explained and in sequence • good understanding of how the nitrogen cycle is a complete cycle of events • soil bacteria/decomposers are referred to appropriately • communicates ideas clearly and uses a range of scientific terminology appropriately. Spelling, punctuation and grammar are used with few errors

Q11. Question Number (i)

Answer

Mark

Indicative Content

(2) Mark

A description including any two from the following points • change in a base from C to T (1) • (causes) change in one codon/triplet of bases (1) • results in a different amino acid (1)

Question Number QWC (ii)

Q12.

Acceptable answers

Level 1

0 1-2

3-4

5-6

An explanation linking some of the following points • enzymes are proteins • mutation in DNA will result in different mRNA stran • during transcription • mRNA leaves the nucleus through the nuclear pore • the attachment of mRNA at the ribosomes • involvement of tRNA and amino acids • at the ribosome • which is translation • amino acid chain/peptide sequence altered • different protein formed/protein not folded correctly (6) No rewardable material • an attempt is made to link the change in the base sequence to the generation of a different amino acid • the answer communicates ideas using simple language and uses limited scientific terminology • spelling, punctuation and grammar are used with limited accuracy • there is evidence that the mutation is linked to a change in the protein • there may be an attempt to explain transcription of the incorrect code and translation of this although this explanation is likely to be unclear and may have missing steps • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately • spelling, punctuation and grammar are used with some accuracy • the response is likely to indicate the type of mutation and link this to a change of codon/protein • the response will show good evidence of understanding that an incorrect mRNA molecule is formed and translation by tRNA will result in an incorrect amino acid being incorporated into the protein chain • the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately • spelling, punctuation and grammar are used with few errors

Question number (a)(i)

Question number (a)(ii) Question number (b)

Question number (c)

Answer

Mark

1 mark for each line Answer

(2) Mark

A Answer

Acceptable answers

(1) Mark

an explanation including the accept to get/to remove following: to release the DNA genetic from the nucleus/break up the material/chromosomes/gen cells (cell walls)/to release the es nucleus or nuclear material (1) gently so that the DNA is not broken up (1) Answer

(2) Mark

an answer describing the process that includes three of the following: identify gene that allows plant to grow in wet or marshy area (1) extract/cut out the gene with a restriction (endonuclease)/enzyme (1) use vector/agrobacterium/ plasmid/to put desired gene into wheat/crop (1)

(3)

Q13. Indicative Content *

Level 1

0 1-2

3-4

5-6

Mark

A description including • fertilisation of egg by sperm • ref to fusion of nuclei • forming diploid cell • ref to zygote • (zygote) divides by mitosis • to form identical cells • several mitotic divisions ( • growth of foetus 6) • examples of how fetus grows eg in height, mass • stem cells in embryo • specialisation / differentiation of (stem) cells into different cell types • examples of different cell types eg neurones, skin cells • development of fetus No rewardable content • a limited description including 2 or more comments about one process • the answer communicates ideas using simple language and uses limited scientific terminology • spelling, punctuation and grammar are used with limited accuracy • a simple description including 2 or more comments on 2 processes • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately • spelling, punctuation and grammar are used with some accuracy • a detailed description including 2 or more comments on all 3 processes • the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately • spelling, punctuation and grammar are used with few errors

Q14. Question number

Q15.

Answer

Mark

a discussion linking three of the following points (in order to gain maximum marks at least one advantage and one disadvantage must be discussed): prevents extinction of species (1) may be possible to clone human body parts (1) reduction in the gene pool (1) potential reduced life expectancy (1)

(3)

Question number (i) Question number (ii)

Answer

Acceptable answers

Mark

12 Answer

accept 4 codons

(1) Mark

any one of: • fossil records do not always form • soft tissues/skin/colour are not preserved • many fossils are yet to be found

(1)

Q16. Question number (a) Question number (b)

Question number (c)

Question number (d)(i)

Question number (d)(ii)

Answer

Mark

C Answer

(1) Mark

any two from: reduced photosynthesis so less carbon dioxide removed from the atmosphere (1) increased decomposition causing microorganisms to release carbon dioxide by respiration (1) if trees are burned, increased combustion releases carbon dioxide (1) Answer Acceptable answers

(2) Mark

an explanation linking the following: guard cells/stomata (become turgid which causes the pore to open) (1) and enable diffusion of CO2 and O2 (1) leaf is thin (1) which allows diffusion of CO2 and O2 (1) Answer

accept air spaces in the spongy mesophyll (1) allow CO2 and O2 to diffuse to and from all cells

Acceptable answers

(2) Mark

7 × 4 (= number of weeds in 1 m2) = 28 (1) 28 × 100 × 180 = 504 000/500 000/half a million (weeds on the field) (1) Answer

credit any correct answer for both marks Transferred error possible Most likely TE being 7 × 100 × 180/126 000 Acceptable answers

(2) Mark

a description to include three of the following: appropriately sized (large) sample (1) measure the perimeter of the area (1) divide area up into equal sized sections (1) use random number generators/tables to select sample areas (1)

Accept belt transect

(3)

Q17. Answer (i)

Acceptable answers

D – ventricle every minute

(1)

Indicative Content *(ii)

Level 1

0 1-2

3-4

5-6

Mark

A description including • there will less blood flow (to the muscles) • because less blood leaving the heart • less oxygen (reaching muscle) • less glucose (reaching muscle) • reduced rate of aerobic respiration • less energy released • less carbon dioxide removed • greater rate of anaerobic respiration • glucose broken down without oxygen • reduced muscle contraction • build up of lactic acid (in muscle cells) • causing cramp / fatigue (6) No rewardable content • a limited description of 2 effects of reduced cardiac output on muscle • the answer communicates ideas using simple language and uses limited scientific terminology • spelling, punctuation and grammar are used with limited accuracy a simple description of 4 or more effects of reduced cardiac output on muscle, but some steps maybe missing or out of sequence • the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately • spelling, punctuation and grammar are used with some accuracy • a detailed description of 6 or more effects of a reduced cardiac output on muscle, with the sequence largely in order and complete • the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately • spelling, punctuation and grammar are used with few errors

Q18. Answer An explanation including two of the following points: • soft tissue of organisms does not form fossils (1) • some fossils are yet to be found (1) • fossils may be damaged (1) • conditions not correct for fossil formation (1) • fossils may only be fragments / not whole organisms (1)

Acceptable answers

Mark

accept: references to plant or animal tissue accept: reasons why they may not be found accept: reasons for damage e.g. earthquakes accept: named conditions e.g. pH

(2)

Q19.

Q20. Question number

Answer

Mark

an explanation that links the following: intestinal wall will have a reduced surface area (1) digested food absorbed less efficiently (1) across the intestinal wall into the bloodstream (1) (so) have low energy/slower growth/more likely to show deficiency diseases (1)

(4)