Past paper questions

Describe a method the farmer could use to reduce the number of greenfly on his crops.

• biological control

• Introduce a predator

• To eat the greenfly

State what is meant by the term allele

A version of a gene

Explain why the actual response time is different from the time taken for a nerve impulse to travel 180 cm

• response time is slower

• Delay between neurons

• Time to generate impulse

• Synapse

• Neurotransmitter

Describe how yeast is used to produce bread

• yeast respires aerobically

• Then anaerobically

• Converses start h into glucose suing amylase

• Producing carbon dioxide

• Which creates air bubbles, causing the bread to rise

Bacteria are small..….. called organisms.

Single

Most of their genetic material is contained in a circular……… of DNA

Chromosome

Other bacteria, such as pneumococcus, cause disease and so are called………..

Pathogen

Where does the placenta develop?

The uterus

Explain why selective breeding in crop plants is easier and quicker than selective breeding with farm animals

• plants produce many more offspring

• Quicker to reach maturity

• Plants can be self pollinated

• Easier to control plants enviroment

Describe how selective breeding can be used to improve milk yield in dairy cattle

• breed bulls, that produce daughters with highest milk yield

• Breed cows that have the highest milk yield

• Breed offspring cows that have highest milk yield of all

• Repeat for many generations

Describe the production of adrenaline and its effects on the body

• produced by adrenal glands

• Causes heart rate to increase

• Prepares body for fight or flight

• Increases blood flow to muscles

• Increases breathing rate

• Increases blood glucose

• Pupils dilate

• Reactions are faster

Describe the role of the placenta in reproduction

• Allows diffusion

• Provides oxygen

• Provides antibodies

• Removes carbon dioxide

• Secretes hormones

What happened when you look at a close object?

Ciliary muscles contract, suspensory ligaments loosen

What happens when you look at a far object?

Ciliary muscles relax, suspensory ligaments pull tight

What happens when you enter a dark room

Radial muscles contract, circular muscles relax, dilating the pupil

What substance is the yeast cell wall made of?

Chitin

Where is bile produced

Liver

Describe the role of bile in digestion

Emulsifies lipids to increase the surface area for digestion, neutralises stomach acid to set the optimum Ph for enzymes

Explain why air is bubbled into the fermenter

Oxygen is required, so the fungus can respire

Explain why the fermenter is cleaned using steam before the fungus and nutrients are added

To kill pathogens, to prevent contamination, steam condenses to water so does not affect the product

Explain the function of oestrogen during the menstrual cycle

Repairs uterus lining for implantation, stimulates release of LH

How does the structure of the placenta enable the efficient exchange of substances between the ferry’s and the mother?

Has a large surface area for diffusion, capillaries bring nutrients and remove waste products, close distance between mother’s and fatal blood for short diffusion pathway

Balanced chemical equation for photosynthesis

6CO2 + 6H2O ——> C6H12O6 + 6O2

What is the function of ribosomes?

Protein synthesis

Describe how lactobacillus bacteria produce yoghurt from milk

Respiration, lactic acid produced, protein clots/milk thickens