Q1.
Figure 1 shows a human body cell.
Figure 1
 
(a)     Which part in Figure 1 contains chromosomes?
Tick one box.
 
A		 	B		 	C		
(1)
(b)     Humans have pairs of chromosomes in their body cells.
Draw one line from each type of cell to the number of chromosomes it contains.
 
Type of cell	 	Number of Chromosomes	
 
 	 	10	
 	 	 	
Human body cell	 	23	
 	 	 	
 	 	46	
 	 	 	
Sperm cell	 	60	
 	 	 	
 	 	92	
(2)
(c)     Humans have two different sex chromosomes, X and Y.
Figure 2 shows the inheritance of sex in humans.
Figure 2
 
Circle a part of Figure 2 that shows an egg cell.
(1)
(d)     Give the genotype of male offspring.
___________________________________________________________________
(1)
(e)     A man and a woman have two sons. The woman is pregnant with a third child.
What is the chance that this child will also be a boy?
 
Tick one box.	 	
    0%		
  25%		
  50%		
100%		
(1)
(Total 6 marks)
Q2.
The drawing shows a potato plant producing new tubers (potatoes). Buds on the stem of the parent plant produce stolons. The new tubers are formed at the ends of the stolons (stems that grow downwards).
 
(a)     Explain why the new tubers are genetically identical to each other.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(b)     Some of the tubers are used to produce potato plants. These new potato plants will not all grow to the same height.
Give one reason why.
___________________________________________________________________
___________________________________________________________________
(1)
(Total 3 marks)
Q3.
Most cows produce milk with a fat content of 3.4%.
Cow S produces milk with a fat content of 1.2%.
Only cow S has the gene to produce this low-fat milk.
(a)     A farmer plans to develop more cows like cow S.
The diagram below shows how the farmer plans to do this.
 
Cow S © GlobalP/iStock/Thinkstock, Bull © Fuse/Thinkstock, Whitish cow © Eric Isselee/iStock/Thinkstock,
Brown cow © DC Productions/Photodisc/Thinkstock, Holstein cow(1) © GlobalP/iStock/Thinkstock,
Holstein cow(2) © GlobalP/iStock/Thinkstock, Calf © Eric Isselee/iStock/Thinkstock. 
(i)      An egg cell from cow S is fertilised by a sperm cell from a bull. This is part of sexual reproduction.
What is the scientific name for sex cells such as egg cells and sperm cells?
______________________________________________________________
(1)
(ii)     After fertilisation, cells are taken from the original embryo.
These cells develop into new embryos.
Which part of the host mother’s body should each new embryo be put into?
______________________________________________________________
(1)
(b)     (i)      The calves born to all of the host mothers are genetically identical to each other.
Draw a ring around the correct answer to complete the sentence.
The calves are genetically identical to each other because
 
they	are formed from the same original embryo.
have the same host mother.
have the same two parents.	
(1)
(ii)     What term is used to describe the method of producing calves shown in the diagram in part (a)?
Tick (✓) one box.
Adult cell cloning		
Embryo transplantation		
Genetic modification		
(iii)    Why are the calves born to the host mothers not genetically identical to cow S?
______________________________________________________________
______________________________________________________________
(1)
(Total 5 marks)
Q4.
In sexual reproduction, an egg fuses with a sperm.
(a)     (i)      Draw a ring around the correct answer to complete the sentence.
 
An egg and a sperm fuse together in the process of	cloning.
fertilisation.
mitosis.	
(1)
(ii)     Egg cells and sperm cells each contain the structures given in the box.
 
chromosome	gene	nucleus	
List these three structures in size order, starting with the smallest.
1 ____________________________________________________ (smallest)
2. ____________________________________________________________
3 _____________________________________________________ (largest)
(2)
(iii)     The egg and the sperm contain genetic material.
Draw a ring around the correct answer to complete the sentence.
 
The genetic material is made of	carbohydrate.
DNA.
protein.	
(1)
(b)     The diagram below shows the inheritance of X and Y chromosomes.
 
(i)      Draw a tick () on the part of the diagram that shows a sperm cell.
(1)
(ii)     What is the chance of having a female child?
Give the reason for your answer.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(Total 7 marks)
Q5.
Kangaroos have brown coats. The two parent kangaroos in the photograph produced a baby kangaroo with a white coat.
 
Photographs supplied by iStockphoto/Thinktsock
(a)       Use words from the box to complete the sentences.
 
asexual	characteristic	chromosome	
mutation	nucleus	       sexual	
The baby kangaroo was produced by _______________________ reproduction.
The coat colour of the adult kangaroo is a _______________________________
The different coat colour of the baby kangaroo is the result of a
________________________________ of a gene.
The gene is found on a thread-like structure called a ______________________
(4)
(b)     Some animals similar to kangaroos are endangered species.
Cloning is one way of making sure that endangered species do not die out.
The flowchart below shows one way of cloning an animal.
The four statements needed to complete the flowchart are numbered 1, 2, 3 and 4.
Complete the flow chart by writing the number of the correct statement in the empty box.
Each number should be used once only.
 
		Remove egg cell from ovary	
		↓	
		______	
		↓	
		The egg cell is now empty	
		↓	
1	Give a small electric shock	______	
2	Transfer nucleus from body cell	↓	
3	Remove nucleus from egg cell	The egg cell now has the nucleus of a body cell	
4	Insert embryo into womb of female	↓	
		______	
		↓	
		Ball of cells	
		↓	
		______	
		↓	
		Cloned animal	
(3)
(Total 7 marks)
Q6.
The diagram shows three types of cells in a life history of a simple animal.
 
(a)     How do the chromosomes of the body cells compare with the chromosomes in the fertilised egg from which they came?
___________________________________________________________________
___________________________________________________________________
(1)
(b)     Describe what happens to chromosomes in the nucleus of a body cell when it forms reproductive cells.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(4)
(Total 5 marks)
Q7.
CRAM is an inherited condition which causes muscle breakdown.
The breakdown products enter the urine, making it dark-coloured.
The diagram below shows the inheritance of CRAM in one family.
 
CRAM is caused by a recessive allele, n.
The allele for normal health is N.
(a)     (i)      What is an allele?
______________________________________________________________
______________________________________________________________
(1)
(ii)     What does recessive mean?
______________________________________________________________
______________________________________________________________
(1)
(iii)    Give evidence from the diagram that CRAM is caused by a recessive allele.
______________________________________________________________
______________________________________________________________
(1)
(b)     (i)      Person 2 is homozygous for CRAM.
What does homozygous mean?
______________________________________________________________
______________________________________________________________
(1)
(ii)     None of person 2’s children have CRAM.
Explain why.
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(c)     Persons 7 and 8 want to have another child.
(i)      What is the probability that this child will have CRAM?
Draw a genetic diagram to explain your answer.
Probability = _____________________________
(4)
(ii)     To avoid having another child with CRAM, persons 7 and 8 may decide to use embryo screening.
Two ways of doing this are:
•        PGD (pre-implantation genetic diagnosis)
•        CVS (chorionic villus sampling).
PGD involves IVF (in vitro fertilisation) of a few eggs, then taking a cell from each embryo when it is 3 days old.
The image below shows how the cell is removed.
 
                    © Rtimages/iStock/Thinkstock
The DNA in the cell can then be tested. An unaffected embryo can be implanted in the woman’s uterus. The possibility of a false positive result is around 1 in 6. The procedure costs about £6000. Affected embryos would be discarded. Extra unaffected embryos might be frozen and kept for later implantation. Alternatively, the extra embryos might be used in scientific research.
CVS involves taking a sample of blood from the placenta a few weeks into pregnancy. DNA from white blood cells can then be tested.
If an affected embryo is detected, the parents then have to decide whether to terminate the pregnancy or allow it to continue.
CVS has a 1 percent chance of giving an incorrect result and a 0.9 percent chance of causing a miscarriage. CVS costs about £600.
Evaluate the benefits of these two methods of embryo screening.
You should include a conclusion to your evaluation.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(5)
(Total 15 marks)
Q8.
Figure 1 shows the stages in the transmission of the malaria parasite by mosquitoes to humans.
Figure 1
 
(a)     Where in the mosquito does Stage 2 happen?
Draw a ring around the correct answer.
 
brain	salivary glands	stomach	
(1)
(b)     What is Organ A in the human?
Draw a ring around the correct answer.
 
liver	pancreas	small intestine	
(1)
(c)     What happens in the human at Stages 5 and 6?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(4)
(d)     Sickle-cell anaemia is an inherited disease caused by a mutation in the haemoglobin gene.
(i)      Genes are small pieces of DNA. The DNA in a gene consists of a sequence of bases.
Figure 2 shows part of the base sequence in the DNA of a normal haemoglobin gene and the same section in the sickle-cell gene. A, C, G and T represent the different bases.
Figure 2
 
Normal gene		GGACTCCTC	
Sickle-cell gene		GGACACCTC	
Describe how the mutation causes a change in the shape of the haemoglobin protein molecule.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(4)
(ii)     Sickle-cell anaemia is caused by a recessive allele, a. The normal haemoglobin allele is dominant, A.
Use a genetic diagram to find the probability that two heterozygous parents will produce a child who is homozygous for sickle-cell anaemia.

 

 

Probability = _______________
(4)
(iii)    What is the benefit of the heterozygous genotype in areas where malaria is common?
______________________________________________________________
______________________________________________________________
(1)
(Total 15 marks)

Mark schemes
Q1.
(a)     A
1
(b)     
 
2
(c)     one x circled under mother
accept if clearly indicated choice even if not circled
1
(d)     XY
allow YX
1
(e)     50 (%)
1
[6]
Q2.
(a)     grow from parents, 
by vegetative reproduction/asexual reproduction/
no sexual reproduction
for 1 mark each
2
(b)     e.g. different environmental conditions/named condition
for 1 mark
1
[3]
Q3.
(a)     (i)      gamete(s)
ignore reproductive cells
1
(ii)     womb / uterus
allow phonetic spellings
1
(b)     (i)      are formed from the same original embryo
1
(ii)     embryo transplantation
1
(iii)    any one from:
•        (calves will have some) genes / DNA from bull / sperm
allow not all genes from the cow
•        idea that sexual reproduction produces variation
allow may be male
allow idea that gene for low fat milk may not be passed on
1
[5]
Q4.
(a)     (i)      fertilisation
1
(ii)     in sequence:
accept 1 next to gene, 2 next to chromosome and 3 next to nucleus in box
1 gene
2 chromosome
3 nucleus
allow 1 mark for smallest or largest in correct position
2
(iii)    DNA
1
(b)     (i)      On diagram:
tick drawn next to X and / or Y from Parent 1
tick(s) must be totally outside grid squares
allow ticks around “parent ”
extra ticks elsewhere cancel
1
(ii)     0.5 / ½ / 50% / 1:1 / 50:50 / 1 in 2
allow 2/4 / 2 in 4 / 2 out of 4 / ‘even(s)’ / ‘fifty – fifty’
do not allow 1:2 or ‘50 / 50’ or ‘50 – 50’
1
2 (out of 4) boxes are XX
or
half of the sperm contain an X-chromosome
allow XY is male and 2 (out of 4) boxes are XY
1
[7]
Q5.
(a)     sexual 
1
characteristic 
1
mutation 
1
chromosome
this order only
1
(b)     
four correct gains 3 marks
two or three correct gains 2 marks
one correct gains 1 mark
accept correct connection between statement and box
3
[7]
Q6.
(a)     idea
          identical (do not allow simply “the same number”)
for 1 mark
1
(b)     idea
          chromosomes double/duplicate/copies made
for 1 mark
          separate into 2 sets/divide*
gains 1 mark
          but
separate into 4 sets/divide twice*
gains 2 marks
          number halved compared to bodycell
or
single set (only) 16
accept in terms of cells but only if chromosomes referred to in 
first and/or last items)
for 1 mark
4
[5]
Q7.
(a)     (i)      alternative / different / one form of a gene
or
a mutation of a gene
do not allow a type of gene
(For info: CRAM = Childhood Recurrent Acute Myoglobinuria)
1
(ii)     not expressed if dominant / other allele is present or it is heterozygous
or
only expressed if dominant allele not present / no other allele present or it is homozygous
need two copies to be expressed / not expressed if only one copy
allow ‘gene’ for allele
1
(iii)    unaffected parents have an affected child
allow 7 and 8 have 10
allow skips a generation
1
(b)     (i)      has two alleles that are the same
accept (person is) nn / NN or has two recessive / dominant alleles
1
(ii)     (all) inherit N / normal / dominant allele from 1 / from father
ignore they are carriers
1
all are Nn / none are nn / all are heterozygous
1
(c)     (i)       genetic diagram including:
1 gametes correct or parental genotypes correct:
N and n  +  N and n    or    Nn  +  Nn
accept alternative symbols, if defined
1
2 derivation of offspring genotypes:
   NN  +  Nn  +  Nn  +  nn
allow alternative if correct for parental gametes
1
3 nn identified as CRAM
accept ¼ / 25% / 1 in 4 / 1 out of 4 / 1:3
1
4 correct probability: 0.25
do not accept 3:1 / 1:4
1
(ii)     any four points + conclusion:
pro PGD:
detected at earlier stage / at 3 days c.f. several weeks / before becoming pregnant
no / less chance of miscarriage c.f. CVS
does not involve abortion / less trauma / less pain / ethical comparison
higher chance of having unaffected child – eg ref to use of spare embryos
provides embryos for research
4
pro CVS:
PGD may destroy some embryos
ethical implications of research on embryos (with PGD)
lower incidence of false positives / false results
low(er) financial cost
conclusion:
must relate to candidate’s argument
must have at least one point from each technique for max marks
1
[15]
Q8.
(a)     salivary gland
1
(b)     liver
1
(c)     any four from:
•        merozoites released (from liver) and enter the red blood cells
•        (some of these) turn into schizonts
•        (which) burst the red blood cells
•        releasing (more) merozoites
•        coincides with fever attacks.
points credited must be in correct sequence
4
(d)     (i)      three bases code for one amino acid
1
middle code of CTC is now CAC / T changed to A
1
so will be a different amino acid (in the chain)
1
(and so chain / protein will have a different shape) due to a different sequence of amino acids
1
(ii)     correct parental genotypes (both Aa)
allow ecf for 2nd and 4th marking points
or correct gametes (A+a   A+a)
allow alternative symbols if defined
1
correct derivation of offspring genotypes from gametes
1
aa identified (homozygous for) SCA
1
0.25
allow 25% or 1 in 4 or 1:3 or 1 / 4
1
(iii)    (Aa) less likely to get malaria (than homozygous dominant / AA)
allow resistance or protection if correctly qualified eg some protection
do not accept ‘immune’
1
[15]