Paper 2-style practice paper: Homeostasis · Inheritance, variation and evolution · Ecology (Higher) — question paper

Section A: Multiple-choice questions[10 marks]

Choose one answer for each question. Each question is worth 1 mark.

1. 1

   The thermoregulatory centre of the body is located in the

   1. Acerebellum
   2. Bmedulla
   3. Chypothalamus
   4. Dretina
   ( )
2. 2

   ADH acts on the kidneys by making the tubules

   1. Afilter faster
   2. Breabsorb more water
   3. Cexcrete more urea
   4. Dmake glucose
   ( )
3. 3

   Meiosis produces

   1. Atwo identical body cells
   2. Bcells with double the DNA
   3. Cclones of the parent cell
   4. Dfour genetically different gametes
   ( )
4. 4

   During protein synthesis, mRNA carries the genetic code to the

   1. Aribosome
   2. Bnucleus
   3. Ccell membrane
   4. Dmitochondrion
   ( )
5. 5

   Cystic fibrosis is caused by inheriting

   1. Aa dominant allele
   2. Ba recessive allele on both copies
   3. Ca missing sex chromosome
   4. Dan extra autosome
   ( )
6. 6

   Speciation occurs when two populations of one species become

   1. Alarger in number
   2. Bbetter at hunting
   3. Creproductively isolated
   4. Dgenetically identical
   ( )
7. 7

   The three-domain system of classification was proposed by

   1. AWoese
   2. BDarwin
   3. CLinnaeus
   4. DMendel
   ( )
8. 8

   Anaerobic decay inside a biogas generator produces

   1. Aoxygen
   2. Bnitrogen
   3. Chydrogen only
   4. Dmethane
   ( )
9. 9

   The efficiency of a biomass transfer is calculated as

   1. Aintake ÷ transferred × 100
   2. Btransferred ÷ intake × 100
   3. Ctransferred × intake
   4. Dintake − transferred
   ( )
10. 10

    Which programme most directly raises the numbers of an endangered species?

    1. Aexpanding landfill
    2. Bdraining peat bogs
    3. Ccaptive breeding
    4. Ddeforestation
    ( )

Section B: Structured questions[90 marks]

Answer all questions in the spaces provided.

1. 11

   This question is about homeostasis, temperature control and reflexes.

   1. (a)

      Define negative feedback and explain why it is needed for homeostasis.

      [3]
   2. (b)

      Describe how the body responds when core temperature rises too high and when it falls too low.

      [4]
   3. (c)

      Describe the pathway of a reflex arc, explaining how the signal crosses each synapse and why the relay neuron sits in the spinal cord.

      [4]
   4. (d)

      In a reaction-time experiment a student records 0.28 s, 0.75 s, 0.30 s and 0.32 s. Calculate the mean reaction time, explaining what you do with the 0.75 s value.

      [3]
2. 12

   This question is about water balance, the kidney and blood glucose.

   1. (a)

      Explain the role of ADH in maintaining the water balance of the blood.

      [4]
   2. (b)

      A person's kidneys fail completely. Explain why they need dialysis or a transplant, and state one advantage of a transplant over long-term dialysis.

      [3]
   3. (c)

      After a meal, blood glucose rises above 90 mg per 100 cm³ and then falls back within two hours. Describe the hormonal control involved, and what happens in a person with untreated type 1 diabetes.

      [4]
   4. (d)

      Explain why the absorption of glucose in the small intestine involves active transport as well as diffusion.

      [3]
3. 13

   This question is about DNA, protein synthesis and cell division.

   1. (a)

      Describe the structure of a DNA molecule.

      [3]
   2. (b)

      Describe the steps of protein synthesis, naming transcription and translation.

      [4]
   3. (c)

      Explain how a mutation in a gene can change the protein it codes for, and describe the possible effects.

      [4]
   4. (d)

      Describe how meiosis produces genetically different gametes.

      [3]
4. 14

   This question is about inheritance.

   1. (a)

      In humans, the allele for free earlobes (F) is dominant to attached earlobes (f). A heterozygous parent (Ff) and an attached-lobed parent (ff) have a child. Draw a Punnett square and give the probability the child has attached earlobes.

      [5]
   2. (b)

      Polydactyly is caused by a dominant allele (P); cystic fibrosis is caused by a recessive allele (c). Explain why a child with polydactyly usually has an affected parent, while a child with cystic fibrosis often has two unaffected parents.

      [4]
   3. (c)

      Complete a Punnett square for the sex chromosomes of a cross between XX and XY parents, and explain which parent determines the sex of the child.

      [4]
   4. (d)

      Describe Mendel's contribution to genetics and suggest why his work was not recognised at first.

      [3]
5. 15

   This question is about evolution and biotechnology.

   1. (a)

      Explain how populations of antibiotic-resistant bacteria evolve.

      [4]
   2. (b)

      Compare selective breeding with genetic engineering, giving one risk or concern for each.

      [4]
   3. (c)

      Explain how geographical isolation can lead to speciation.

      [4]
   4. (d)

      Describe adult cell cloning, and give one ethical concern about cloning animals.

      [4]
6. 16

   This question is about ecosystems.

   1. (a)

      Describe the four processes that move carbon through the carbon cycle, and state the role of decomposers.

      [4]
   2. (b)

      Grass contains 800 kJ of biomass energy. Rabbits eating the grass build 120 kJ of new biomass; foxes eating the rabbits build 18 kJ. Calculate the efficiency of each transfer, to the nearest whole number.

      [4]
   3. (c)

      Explain two ways human activity reduces biodiversity and describe one programme that helps maintain it.

      [4]
   4. (d)

      Describe two biological threats to global food security and one response, with a trade-off.

      [4]