Top answers

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 concentrati...
DA
Answered by Daniel A. • Biology tutor
3544 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 hyd...
DV
Answered by Daniel V. • Biology tutor
2946 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 allele ...
LN
Answered by Laura N. • Biology tutor
3049 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.
LN
Answered by Laura N. • Biology tutor
4156 Views

What is the definition of osmosis?

Osmosis is the process describing the random movement of water molecules through a permeable membrane from an area of high water concentration to an area of low water concentration until equilibrium is reached.
FM
Answered by Finlay M. • Biology tutor
4180 Views