Biology Mixed Questions

Biology Mixed Questions

Q1.

(a) Complete the sentence by putting a cross ( ) in the box next to your answer.

Food is moved through the digestive system by

(1)

A diffusion

B digestion

C peristalsis

D active transport

(b) State two roles of bile in digestion.

(2)

*(c) Describe the roles of the enzymes involved in digestion.

(6)

(d) Explain how the structure of the villi allows efficient absorption in the small intestine.

(3)

(Total for Question is 12 marks)

Q2.

The photograph shows a sperm cell and an egg cell just before fertilisation.

Describe the structure of DNA.

(3)

Q3.

(a) Describe how a section of DNA determines the structure of a protein.

(4)

*(b) Describe the structure of DNA, including the roles of the scientists involved in its discovery.

(6)

Human DNA was sequenced during the Human Genome Project.

(2)

(Total for Question is 12 marks)

Q4.

The family pedigree shows the inheritance of sickle cell disease through three generations.

(i) Calculate the percentage of the offspring from the first generation who are heterozygous for sickle cell disease.

(1)

(ii) Explain why the offspring produced by the first generation parents are not the same as those predicted in a Punnett square.

(2)

(iii) Person W and his partner have a third child.

State the probability that this child will have sickle cell disease.

Complete the Punnett square to show this.

(2)

(iv) Complete the sentence by putting a cross ( ) in the box next to your answer.

The genotype of person V is

(1)

A homozygous dominant

B homozygous recessive

C heterozygous

D carrier

Q5.

(a) Purple tomatoes are transgenic plants that have been produced by genetic engineering.

(i) As a result of genetic modification, these tomatoes produce a new substance which has health benefits and turns the tomatoes purple.

Name this substance.

(1)

(ii) What is inserted into the DNA of another plant to make it transgenic?

Put a cross ( ) in the box next to your answer.

(1)

A a gene from another species

B a gene from the same species

C chromosomes from the same species

D proteins from another species

*(b) Describe how Agrobacterium tumefaciens can be used to create transgenic plants.

(6)

Explain one advantage and one disadvantage of introducing this gene into crop plants.

(4)

(Total for Question = 12 marks)

Q6.

Height can be used to monitor growth.

(a) The graph shows a percentile chart for height for males aged between 2 and 20 years.

(i) Describe how the height of males changes from the age of 2 to 20 years.

(2)

(ii) Calculate the difference in height of an 11 year old male in the 95th percentile and an 11 year old male in the 5th percentile.

(2)

(iii) Explain what is meant by the 95th percentile on this graph.

(2)

(b) Protein is needed for growth.

(i) Name the first stage of protein synthesis.

(1)

(ii) Complete the sentence by putting a cross ( ) in the box next to your answer.

The second stage of protein synthesis produces a

(1)

A polypeptide made of amino acids

B polypeptide made of bases

C strand of mRNA made of amino acids

D strand of mRNA made of bases

(Total for Question is 8 marks)

Q7.

Describe how fossil evidence can be used to show that humans have evolved.

(2)

......

Q8.

Huntington's disease is a genetic disorder.

The genetic diagram shows the inheritance of this disorder.

(a) (i) Use words or letters from the box to complete the following sentences.

(2)

Huntington's disease is caused by a ...... allele.

People with Huntington's disease can have the genotype Hh or ......

(ii) Complete the Punnett square to show the potential offspring of two parents heterozygous for Huntington's disease.

(2)

(iii) State the probability that a child of two parents, heterozygous for Huntington's disease, will have the disease.

(1)

......

(b) The genetic diagram shows the inheritance of cystic fibrosis.

(i) Explain why, if both sets of parents are heterozygous, the chance of inheriting Huntington's disease is greater than the chance of inheriting cystic fibrosis.

(2)

......

(ii) Complete the sentence by putting a cross () in the box next to your answer.

A symptom of cystic fibrosis is the overproduction of

(1)

A mucus

B red blood cells

C stomach acid

D white blood cells

(iii) Explain why a man with cystic fibrosis may be infertile.

(2)

......

Mark Scheme

Q1.

Answer / Acceptable answers / Mark
(a) / C peristalsis / (1)
(b) /
· neutralisation (of stomach acid) / raise pH (1)
· emulsification / break down of fats (1) / Accept makes stomach / intestine contents more alkaline Accept breaks down large droplets /globules / increases surface area of fats Reject molecules broken down / (2)
Indicative Content / Mark
QWC / *(c) / A description including some of the following points in a logical sequence Names of enzymes:
· carbohydrases
· named carbohydrase eg amylase
· proteases
· named protease eg pepsin
· lipases
· named lipaseGeneral points about enzyme action:
· breakdown of large / insoluble / named molecules into small / soluble / named molecules
· for absorption
· catalysts
· speeds up reactions
· active sites that bind to substrate
· idea of specificitySpecific points:
· carbohydrates/ starch are broken down
· into sugars / glucose
· proteins /named protein are broken down
· into amino acids
· fats / oils / lipids / named lipid are broken down
· into fatty acids /glycerol / (6)
Level / 0 / No rewardable content
1 / 1 - 2 /
· a limited description of enzyme action that includes at least three points
· the answer communicates ideas using simple language and uses limited scientific terminology
· spelling, punctuation and grammar are used with limited accuracy
2 / 3 - 4 /
· a simple description of enzyme action that includes at least six points
· 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
3 / 5 - 6 /
· a detailed description of at least nine points
· the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately
· spelling, punctuation and grammar are used with few errors
Answer / Acceptable answers / Mark
(d) / An explanation linking three of the following points
· (E) more /fast / maximises diffusion / absorption (1)
· (S) microvilli (1)
· (E) large surface area (1)
· (S) single layer of cells / one cell thick / thin walls (1)
· (E) small diffusion distance (1)
· (S) capillary network / good blood supply / capillaries inside villus (1)
· (E) maintains diffusion gradient (1) / To award all three marks at least one structure (S) and explanation (E) must be linked together. Award once, linked to any structure Ignore efficient (in stem) / easier Reject ref to cell wall / (3)

Q2.

Q3.

Answer / Acceptable answers / Mark
(a) / A description including the following linked points
· ref to a gene (coding for protein)(1)
· sequence of bases determines sequence of amino acids (1)
· idea of one code / triplet / codon / 3 bases (for one amino acid) (1)
· several amino acids make up a protein / (poly)peptide (1)
· transcription / detail of transcription (1)
· translation / detail of translation (1) /
Accept on either DNA or RNA base pairs
Accept a chain of amino acids
eg mRNA made
eg mRNA attached to ribosome / (4)
Indicative Content / Mark
QWC / *(b) / A description including some of the following points in a logical sequence Points relating to DNA structural features:
· two strands
· double helix
· (contains) bases
· A, T, C, G
· adenine / A paired with thymine / T
· guanine / G paired with cytosine / C
· hydrogen / H bonds joining basesContributions from Scientists:
· X-ray (crystallography) being used
· to show helical structure
· to show diameter of molecule
· how base pairs are arranged was shown
· how strands are arranged was shown
· modelling
· reference to using other people's ideas / (6)
Level / 0 / No rewardable content
1 / 1 - 2 /
· a limited description that includes either: at least three DNA features OR one contribution
· the answer communicates ideas using simple language and uses limited scientific terminology
· spelling, punctuation and grammar are used with limited accuracy
2 / 3 - 4 /
· a simple description that includes at least three features of DNA and at least one contribution OR two features of DNA and two contributions.
· 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
3 / 5 - 6 /
· a detailed description of the structure of DNA that includes at least three features and two contributions.
· the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately
· spelling, punctuation and grammar are used with few errors
Answer / Acceptable answers / Mark
(c) / An explanation to include two of the following points linked together
· genes / base sequence (on human chromosome) identified (1)
· identification of faulty / mutated genes (1)
· people can be tested for a genetic disorder (1)
· ref to development of gene therapy (1)
· idea that appropriate /early /personalised / genomic medication / counselling can be given (1) / Accept base pair sequence gene map Accept idea that genes can be linked to disease Accept diagnosis of cancer
Accept a description of gene therapy / (2)

Q4.

Answer / Acceptable answers / Mark
(i) / 75% / (1)
(ii) / An explanation linking two of the following:
· Punnett square would predict 50% normal 50% carrier (1)
· actual offspring are not 50% carrier (1)
· the probability is applied to each child not the overall offspring (1) / accept ratios or probabilities instead of percentages
actual offspring are 75% accept references to random assortment / (2)
(iii) / Probability = 50%
Ratio 2/4, 2:2, can be given for probability 1 mark for correct gametes 1 mark for completed Punnett square with correct probability / Accept reverse order for gametes Accept letters other than B/b (but alleles must be the same letter) 50% mark can only be given if 50% of the offspring are homozygous recessive / (2)
(iv) / Ahomozygous dominant (BB) / (1)

Q5.

Answer / Acceptable answers / Mark
(a) (i) / flavonoids / bioflavonoids / anthocyanins
antioxidants / (1)
(a) (ii) / A a gene from another species / (1)
Indicative Content / Mark
QWC / *(b) / A description including some of the following points genetic modification
· transferring a gene from one organism to another
· restriction enzymes to cut the gene out
· plasmids used to carry gene
· sticky ends to join complementary bases
· ligase to join the DNAuse of Agrobacterium
· Agrobacterium is a vector (for the gene)
· the Agrobacterium has a suitable gene added to it
· example of a suitable gene eg drought resistance / insect resistance / larger yield / for flavonoids
· Agrobacterium naturally invades plant cells
· its DNA is incorporated into the plant's DNAproduction of plants
· plant sprayed with Agrobacterium
· crown gall (formed)
· crown gall is cut into small pieces
· leaf discs are incubated with Agrobacterium
· (crown gall tissue / leaf discs) grown in tissue culture
· explants
· grown into crops / (6)
Level / 0 / No rewardable content
1 / 1 - 2 /
· a limited description of at least one of the areas involved in creating transgenic plants. Steps may be missing or out of sequence.
· the answer communicates ideas using simple language and uses limited scientific terminology
· spelling, punctuation and grammar are used with limited accuracy
2 / 3 - 4 /
· a simple description of at least two of the areas involved in creating transgenic plants or a detailed description of one area involved in creating transgenic plants
· 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
3 / 5 - 6 /
· a detailed description of the genetic modification, use and production of transgenic plants. Steps should be in sequence.
· the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately
· spelling, punctuation and grammar are used with few errors
Answer / Acceptable answers / Mark
(c) / An explanation of one advantage for two marks
· crop produces a toxin that kills insects (that eat plant)(1)
· so less damage by insect / increased crop yield (1)
· less man-made chemicals used / specific to pests / less pollution (1)An explanation of one disadvantage for two marks
· cross pollination / fertilisation with other plants (species) (1)
· producing weeds that contain the toxin(1)
· non target organisms may be affected (1)OR
· idea of large areas of monocultures (1)
· reduction in insect numbers / biodiversity (1)
· negative impact on food chains (1)OR
· GM crops cost more (1)
· Farmers cannot afford them / become reliant on them (1) / accept references to ICP accept does not kill other insects / (4)

Q6.