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Explain the three stages of drug testing.

First, drugs are tested on human cells and tissues, it is then tested on two different mammals. The final stage has two parts, the drug is initially tested on healthy human volunteers and they are given i...

Answered by Yasmin A. • Biology tutor

3252 Views

How would you investigate the effect of light intensity on the rate of photosynthesis in pondweed? [6]

Apparatus is set up by first adding the pondweed to a beaker filled with water. The beaker has been sealed and any gas produced by will be collected by a syringe. Light will be provided by a lamp and its ...

Answered by boland S. • Biology tutor

25894 Views

Describe the three different types of point mutation, and explain for each what the effect on the final gene product is likely to be

Base insertion/addition. This is when a base pair is added to a sequence - for example AGTCGTAGC could become AGTCGATAGC. In this situation, a frame shift occurs, and every c...

Answered by Rachel H. • Biology tutor

4542 Views

Give the name and describe the process by which macrophages kill pathogens.

Phagocytosis. Macrophage picks up signals of pathogen, extends cytoplasm around pathogen and engulfs it in a vesicle. Lysosomes diffuse towards the vesicle through the cytoplasm, fuse and the (lytic) enzy...

Answered by Isabel B. • Biology tutor

2509 Views

What is the difference between the xylem and phloem?

the xylem transports water and minerals the plants need. water is taken up from the roots normally and is needed at the leaves. so the direction of flow in the xylem is only upwards. also is made of dead ...

Answered by Najma A. • Biology tutor

3119 Views