Unofficial AQA Biology Unit 3 GCSE NEW SPEC Mark Scheme

1.

Coronary Artery

2.

Stents

3.

Stents are metal mesh tubes inserted into blood vessels to expand them if they are blocked, for example by fatty deposits or cholesterol. They are placed in surgery using an inflated balloon. It increases the blood vessel size at the blockage to allow blood to flow more effectively.

1.

The second food chain (wheat→pigs→humans) has more steps and wastes more energy because the pigs use energy in respiration for movement, homoeostasis, etc. The first food chain (wheat→human) provides ten times more energy than the second food chain.

2.

Factory farming is when food production is made more efficient by reducing energy loss and maximising growth.

Animals are kept in a small space or cage which reduces land requirements. This provides more space for other crops or resources and, so, more food is produced in a smaller space. This is more profitable and creates a larger yield or more produce. However, it is easier for animals to catch diseases off one another and it is expensive to monitor diseases.

Animals' movement is, also, restricted. This reduces energy loss by movement and creates full-size animals quickly. This is more profitable and creates a larger yield or more produce. However, it is seen as cruel, unethical and inhumane as it restricts the animals' freedom- against animal rights. Moreover, stressed animals gain weight less quickly then non-stressed animals.

Moreover, animals are kept warm and indoors. Therefore, less energy is expended by the animal on heating itself, homoeostasis. More energy is used for growth. This quickens the growing process and more profit in the long-term. But, it can be expensive to heat the animals and causes an indirect CO2 increase as fuels are burnt to produce heat energy.