Search our library of homework questions

Top answers

All subjects

All levels

Why does as an excess of nutrients such as nitrates lead to animal death in bodies of freshwater?

This is an unexpected result as usually nutrients are considered beneficial to organisms. Some organisms do benefit enourmously from the nutrients, but this leads to the deaths of other. The high concentr...

Answered by Daniel A. • Biology tutor

2771 Views

Consider an isosceles triangle ABC, where AB=AC=1, M is the midpoint of BC, and <BAM=<CAM=x. Use trigonometry to find an expression for BM and by finding BC^2, show that cos2x = 1 - 2(sinx)^2.

Consider the right-angled triangle BAM. We have the hypotenuse and an angle, and want to find the opposite side. Therefore, using SOHCAHTOA, sinx = BM/1, hence BM = sinx. Because M is the midpoint of BC, ...

Answered by Blessie S. • Maths tutor

5642 Views

How is immunity developed after a primary infection by bacteria?

Phagocytosis - A phagocyte detects the bacteria has foreign antigens and so envelops it with its cytoplasm, packaging it into a phagosome via endocytosis. Lysosomes then fuse with the phagosome releasing ...

Answered by Daniel V. • Biology tutor

2312 Views

In some parts of Africa, where malaria commonly occurs, there are higher frequencies of the allele that causes sickle-cell anaemia.

Individuals with the recessive sickle-cell anaemia allele have a lower chance of developing severe malaria. Therefore, they are more likely to survive and reproduce than those without the allele. The alle...

Answered by Laura N. • Biology tutor

2261 Views

Describe the differences between active transport and facilitated diffusion.

Facilitated diffusion is a passive process that occurs down a concentration gradient. Active transport requires energy (from ATP) to allow movement of substances against a concentration gradient.

Answered by Laura N. • Biology tutor

3035 Views