Top answers

Describe the process of evolution (6 Marks)

Mutations in genetic code occur naturally leading to different alleles in genes. (1 mark) This leads to variation within a species. (1 mark) Variation provides some individuals with traits which mean they ar...
JW
Answered by Jack W. • Biology tutor
21032 Views

Describe the ways in which LDLs and HDLs affect the formation of atheromas.

Remember that often in A-level exams you can get marks from specific key words and phrases, so first of all try to remember everything you know about the topics in the question ( HDLs , LDLs and atheromas )....
ID
Answered by Iona D. • Biology tutor
12261 Views

How is the diffusion of gases between the alveoli and the alveolar blood vessels facilitated?

Alveoli are small sacs at the end of the terminal branches of the lung (the brochioles). It is at the alveoli where gas exchange takes place - oxygen moves into the blood and carbon dioxide is removed. The b...
KC
Answered by Katy C. • Biology tutor
15281 Views

What is homeostasis?

Homeostasis is defined as the maintenance of a constant internal environment in the body. An example of this would be the blood glucose level: After a meal, a person's blood glucose level would be high. This...
LS
Answered by Lauren S. • Biology tutor
5633 Views

How do bacteria acquire resistance to antibiotics?

Spread of mutations via vertical and horizontal transmission Once a bacterium has a mutation that provides resistance to an antibiotic, it can spread through replication or through direct transmission to oth...
HL
Answered by Hannah L. • Biology tutor
8584 Views