Search our library of Biology A Level questions

Top answers

Biology

A Level

Describe the control of the menstrual cycle by the hormones FSH, LH, Oestrogen and Progesterone, in the situation where the person does not become pregnant. You may use a diagram to show how their levels change throughout the cycle.

Day 1-5: FSH is released from the pituitary gland and stimulates the primary oocytes to complete meiosis 1 and mature. The primary oocyte is inside a primary follicle which matures into a Graafian follicl...

Answered by Udita D. • Biology tutor

2553 Views

What is the function of the kidneys and how do they carry this out?

Broadly speaking, the main function of the kidneys is to filter out waste from the body and excrete it out in the urine. Excretion is the removal of waste (i.e. products of metabolism/ toxic products like...

Answered by Mannat R. • Biology tutor

2395 Views

Describe the role of two named enzymes in the process of semi-conservative replication of DNA

DNA helicase breaks the hydrogen bonds between DNA strands, separating the double-stranded DNA into single strands and exposing the nucleotide bases.DNA polymerase joins adjacent DNA nucleotides through f...

Answered by Maddy C. • Biology tutor

11770 Views

How is an Action Potential transmitted across a synapse?

-An action potential arrives at the presynaptic membrane-Ca²⁺ ion channels open-Ca²⁺ions diffues into presynaptic knob-Acetylcholine/ neurotransmitter in vesicles-Vesicles move towa...

Answered by Darcie W. • Biology tutor

2239 Views

How is the structure of DNA related to its function

The sugar-phosphate backbone is double stranded so protects the bases; DNA is a large molecule so can store lots of information; DNA is coiled so compact;Base sequence codes for amino acids; DNA is double...

Answered by Ishaq H. • Biology tutor

4567 Views