1. 1
   A microbiologist at a vaccine research laboratory examines a sample of bacteria, a prokaryotic cell, and compares it with a white blood cell taken from a blood sample, a eukaryotic animal cell.

   (a)

   Which structure is found in the bacterial cell but not in the white blood cell?

   [1 mark]

   • ANucleus
   • BMitochondria
   • CPlasmid
   • DCell membrane

   (b)

   In the bacterial cell, where are most of its genes located?

   [1 mark]

   • AIn the cytoplasm, not enclosed in a nucleus
   • BIn a distinct nucleus
   • CIn the mitochondria
   • DIn the cell wall

   (c)

   Describe two structural differences (other than the presence of a nucleus) between the bacterial cell and the white blood cell.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A butcher preparing cuts of meat for a customer points out a piece of stomach tissue from a cow, which contains muscular tissue, glandular tissue and epithelial tissue all working together as part of the digestive system.

   (a)

   Which term describes a group of cells with similar structure and function, such as the muscular tissue in the stomach wall?

   [1 mark]

   • AOrgan
   • BOrgan system
   • COrganelle
   • DTissue

   (b)

   What is the main function of the glandular tissue in the stomach wall?

   [1 mark]

   • ATo contract and move food through the digestive system
   • BTo produce digestive juices
   • CTo cover the inside and outside of the stomach
   • DTo absorb digested food into the blood

   (c)

   Explain why the stomach is described as an organ rather than a tissue.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A biology class compares a cross-section of a young stem from a dicotyledonous plant with the layout of the human digestive system, to see how organisation into tissues, organs and systems applies to very different organisms.

   (a)

   Identify three different tissues that could be found in the young stem, and state one function of each.

   [3 marks]

   (b)

   Describe how the human digestive system, as an organ system, includes organs and glands that work together, using three named examples in your answer.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A biology teacher explains to a class why the size and complexity of an organism affects how it is organised, using the example of a single-celled amoeba compared with a large multicellular mammal.

   (a)

   Explain why a single-celled organism such as an amoeba can exchange all the substances it needs directly across its cell membrane, but a large multicellular organism such as a mammal cannot, and explain how mammals overcome this problem.

   [6 marks]

   (b)

   Describe how cells become specialised in a multicellular organism such as a mammal, and explain, using the levels of organisation, how these specialised cells are built up into a working organism.

   [6 marks]

   Total for question 4: 12 marks

5. 5
   A freshwater fish has a much higher concentration of salts inside its blood than in the pond water surrounding it. Its gill cells take in the salts it needs by active transport, while oxygen enters the blood by diffusion across the same gill surface.

   (a)

   Which statement correctly describes active transport?

   [1 mark]

   • AThe movement of particles from a high to a low concentration, requiring no energy
   • BThe movement of particles from a low to a high concentration, requiring energy from respiration
   • CThe diffusion of water across a partially permeable membrane
   • DThe movement of particles down a concentration gradient using energy

   (b)

   Why can oxygen move into the fish's blood across the gill surface without using energy?

   [1 mark]

   • ABecause oxygen moves from a lower concentration in the water to a higher concentration in the blood, by active transport
   • BBecause oxygen is actively pumped across the membrane by the gill cells
   • CBecause oxygen moves by osmosis through the partially permeable gill membrane
   • DBecause oxygen moves down its concentration gradient, from a higher concentration in the water to a lower concentration in the blood, by diffusion

   (c)

   Explain why the fish's gill cells need to use active transport, rather than diffusion, to take in the salts they need from the pond water.

   [2 marks]

   Total for question 5: 4 marks

6. 6
   A botanist examines a leaf and identifies that it is made up of several different tissues, including the epidermis, palisade mesophyll and spongy mesophyll, each contributing to the leaf's role as a photosynthetic organ within the plant's system for gas exchange and food production.

   (a)

   Which tissue in the leaf is the main site of photosynthesis, due to containing the most chloroplasts?

   [1 mark]

   • APalisade mesophyll
   • BEpidermal tissue
   • CSpongy mesophyll
   • DXylem

   (b)

   What is the function of the air spaces found in the spongy mesophyll tissue?

   [1 mark]

   • ATo store water for photosynthesis
   • BTo transport sugars away from the leaf
   • CTo facilitate diffusion of gases within the leaf
   • DTo absorb light energy

   (c)

   Explain how the leaf is an example of organisation into tissues that form an organ within a system.

   [2 marks]

   Total for question 6: 4 marks

7. 7
   A plant physiologist compares a root hair cell, which is adapted for absorbing water and mineral ions from the soil, with a palisade mesophyll cell, which is adapted for photosynthesis, to show how cell structure relates to function.

   (a)

   Describe how the root hair cell is adapted for absorbing water and mineral ions from the soil, and name the processes it uses to take up these substances.

   [3 marks]

   (b)

   Describe two structural features of a palisade mesophyll cell that adapt it for photosynthesis, and explain how each feature helps the cell carry out its function.

   [4 marks]

   Total for question 7: 7 marks

8. 8
   A school gardening club plants a row of young bean seedlings. Over several weeks, the students investigate how the seedlings grow, develop specialised tissues and organs, and exchange materials with their environment.

   (a)

   Describe how the bean seedling's roots, stem and leaves are organised into tissues and organs, and explain how xylem and phloem tissue enable transport of substances between these organs.

   [6 marks]

   (b)

   Explain how diffusion, osmosis and active transport each allow the bean seedling to exchange substances with its environment, giving one named example of each process occurring in the seedling.

   [6 marks]

   Total for question 8: 12 marks

End of questions