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What are the main components and properties of a plasma membrane?

A plasma membrane is composed mainly of an unordered phospholipid bilayer (double layer) embedded with membrane proteins which forms a thin flexible sheet. This gives the...

Answered by Katie D. • Biology tutor

23683 Views

Describe the effects of cigarette smoke on the airway.

Cigarette smoke contains a number of harmful chemicals such as Tar, Carbon monoxide and Nicotine.

Tar settles on the lining of the airway and alveoli, increasing the diffusion distance for the gase...

Answered by Kristen D. • Biology tutor

5718 Views

What are Enzymes and how do they work?

What is an Enzyme?
Enzymes have an essential role in the reactions in the body from respiration to digestion. Enzymes are globular proteins with a specific tertiary shape.

Answered by Katie D. • Biology tutor

22150 Views

What is the difference between excretion and egestion? Name three major organs of excretion in humans, the substances they excrete and the function of this excretion.

Excretion is the removal of toxic materials, waste products of metabolism and excess substances from organisms.

Egestion is the passing out of undigested food as faeces, through the anus.

Th...

Answered by Lucy W. • Biology tutor

110658 Views

Why do plants grow towards sunlight?

Plants have adapted to grow towards sunlight - an essential requirement for growth and survival. But how do they do this? An important factor in the control of plant growth is the hormone 'auxin', found w...

Answered by Rachael D. • Biology tutor

17192 Views