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Section A: Organisms and Life Processes

Chapter 1: Life processes 1 eight respiration excrete move reproduce stimuli internal environment

2 a) Neat clear diagram, labelling nucleus, cell membrane, cytoplasm, mitochondria

b) Minimal answers:

nucleus contains the genetic material and controls the cell activities

cytoplasm a liquid gel where many chemical reactions take place

cell membrane controls the movement of substances into and out of the cell

mitochondria provide the cell with energy through respiration

3 a) Nucleus, cell membrane, cytoplasm, cell sap, mitochondria, vacuole, cell wall, chloroplast

b) Cell wall made of cellulose to strengthen the cell and give it support

Vacuole a space in the cytoplasm filled with cell sap that helps to keep the cell rigid

Chloroplasts found in the green parts of the plant. They contain green chlorophyll, which absorbs light energy for photosynthesis.

c) The plant root cell would not contain any chloroplasts because the roots are underground, dont get any light and dont carry out photosynthesis, so they dont need chlorophyll.

4 a) Amylase breaks down starch. The evidence is that iodine no longer turns black to indicate the presence of starch.

b) An increase in temperature increases the speed of the reaction.

c) As a control, to make sure that starch wouldnt break down anyway.

d) It wouldnt work as well, in fact it would probably stop working completely, because a change in pH causes a change in the shape of the active site, which affects the ability of the enzyme to catalyse the reaction.

5 a) Glucose + oxygen carbon dioxide + water + energy

b) Lactic acid

c) Aerobic respiration produces water and carbon dioxide as waste products, plus a lot of energy. Anaerobic respiration produces only lactic acid and less energy.

6 a) Because blood travels through the water by diffusion and sharks follow the diffusion gradient

b) Net movement of particles = movement of particles in movement of particles out

c) Temperature, concentration, available surface area

7 a) There is a lower concentration of water molecules in the partially permeable membrane bag than in the surrounding pure water. Water moves into the bag by osmosis down a concentration gradient. The bag fills and water is forced up the glass tube.

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b) The situation would be reversed. There would be a higher concentration of water molecules in the bag than in the surrounding solution. Water would move out of the bag by osmosis into the surrounding solution. The level of water in the tube would drop and the bag would become flaccid.

c) Osmosis is a specialised case of diffusion. It is the diffusion of water down a concentration gradient through a partially permeable membrane.

8 a) Cells that are specialised and adapted to carry out particular functions in the body

b) The number of mitochondria in a cell reflects the amount of energy needed by the cell, so a cell with many mitochondria will tend to be a very active cell, either dividing, contracting or producing chemicals such as hormones or enzymes.

c) i) A group of cells specialised for a particular function. Any sensible example, e.g. muscle

ii) Several tissues working together to carry out a function in the body. Any sensible example, e.g. heart

iii) Several organs working together to carry out a function in the body. Any sensible example, e.g. circulatory system, digestive system

d) Suitable diagram could be as simple as

cell tissue organ organ system body

Chapter 2: The variety of living organisms 1

Type of organism Example Way(s) of feeding Multicellular?

animal cow eats other organisms/plants yes

plant [any plant] makes own food yes

protoctist [any protoctist] eats other organisms or makes own food

sometimes

Bacterium (prokaryote) [any bacterium] eats other organisms or makes own food

no

virus [any virus] doesnt feed no

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2 a) Examples:

Plants Animals

multicellular multicellular

cells contain chloroplasts cells do not contain chloroplasts

cells have cellulose cell walls cells can change shape

carry out photosynthesis feed on other organisms

main carbohydrate storage compound is starch main carbohydrate storage compound is glycogen

do not move whole organism around move whole body in coordinated way

b) Any sensible difference, e.g. plants photosynthesise, fungi do not; plant cell walls are made of

cellulose, fungal cell walls are made of chitin; any sensible similarity, e.g. both have cell walls.

3 a) Grouping living organisms based on similarities of structure and function

b) Features that have a similar evolutionary background / strong similarity of structure and function

c) Vertebrates have backbones (vertebral columns); invertebrates do not.

4 a) Any sensible answer, e.g. yeast, mushroom, mould, etc.

b) Fungi dont contain chlorophyll, so they cant photosynthesise. They contain chitin in their cells walls, not cellulose.

c) i) Thread-like filaments that make up the main body of a fungus

ii) The whole network of hyphae

iii) The reproductive cell of a fungus

5 a)

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b)

c) i) The hyphae secrete digestive enzymes onto the food. The enzymes break the food down into soluble molecules such as sugars, which are then absorbed by the mould. (They are known as extracellular enzymes.)

ii) Saprotrophic / saprophytic nutrition

6 A cell wall, B chromosome/genetic material, C flagella, D plasmids, E slime capsule, F genetic material, G protein coat

7 a) Bacteria 15 m long, viruses 0.010.1 m in diameter

b) Bacteria feed, respire, reproduce, grow, excrete, etc. all characteristic of living organisms. Viruses only reproduce in the cells of a living host they dont carry out any of the other characteristics of a typical living organism.

c) Bacteria can be very useful decomposition, making food, etc., although they can also cause disease. All natural viruses cause disease.