Top answers

Describe and explain two ways in which alveoli in the mammalian lung are adapted for efficient gaseous exchange

Alveoli in the mammalian lung are thin walled to allow the quick passage of gases, for example oxygen and carbon dioxide. Alveoli in the mammalian lung have a large surface area which allows for the diffusio...
GA
Answered by Guy A. • Biology tutor
3516 Views

Explain how DNA is replicated and why this is important in biology.

When cells divide by cytokinesis the nucleus also has to divide so that each new cell contains a nucleus with a complete copy of all of the genetic information. DNA replication therefore needs to ensure that...
DS
Answered by Danya S. • Biology tutor
14021 Views

How does the wave of conduction pass through the heart?

Firstly, the 'wave of excitation' is produced by the sinoatrial node (SAN) in the top of the right atrium - this is also known as the pacemaker, as this is what controls the rate of contractions. This wave p...
EB
Answered by Elisabeth B. • Biology tutor
10568 Views

Explain how an action potential is generated

When a neurone is stimulated an action potential is generated by a change in ion concentrations across the cell membrane. The resting membrane potential (the potential of charge across the membrane when the ...
SJ
Answered by Suraiyya J. • Biology tutor
37638 Views

Describe the processes and forces that allow water movement up a plant stem.

Water moves into the plant stem from the soil, and up to the leaves via the xylem. Water is taken up by the hairs on the root of the plant down the water potential gradient via osmosis, following the active ...
HC
Answered by Hannah C. • Biology tutor
18780 Views