Top answers

How does translocation occur in the phloem?

Active transport occurs at the source, loading assimilates e.g. from photosynthesis in a leaf. This is carried out by specialised companion cells, via active pumping of hydrogen ions out of the cell, and cot...
JL
Answered by Julie L. • Biology tutor
7127 Views

What are the structural and functional differences between arteries and veins?

Arteries have a much thicker muscular layer than veins, as this allows them to contract strongly and generate a high pressure to allow blood to be quickly transported to tissues in the body. Arteries also ha...
AR
Answered by Anita R. • Biology tutor
3340 Views

Name and outline the two types of circulatory systems

A single circulatory system is where blood flow starts with deoxygenated blood being pumped by the heart to the lungs or gills and then travelling directly to the rest of the body’s tissues. Found in fish an...
BS
Answered by Bianca S. • Biology tutor
8169 Views

How does an action potential work?

Resting potential at - 75mV Stimulus causes opening of sodium channels and influx of sodium ions, membrane becomes less polarized Threshold potential reached at -55mV, opening of many more sodium channels, g...
CH
Answered by Catherine H. • Biology tutor
3353 Views

What is the electron acceptor used in photosynthesis

NADP
BS
Answered by Bianca S. • Biology tutor
3214 Views