bio final

describe the graph trend between pepsin and trypsin

there is a contrasting pH optimum, pepsin is highly acidic while trypsin is slightly alkaline

optimum pH for trypsin

8

explain why there is no trypsin activity at pH 5

works best in alkaline conditions, with an optimum pH of around 8, too high or too low pH alters the active site shape and denatures the enzyme

how can temperature be controlled in investigation

water bath or incubator set to a constant temperature

what pathogen causes malaria

protist

state how the pathogen that causes malaria is spread

transmitted to humans through the bites of infected mosquitoes which then multiply

explain one conclusion that can be made about the changes in number of measle cases reported from 1985 to 2015

suggests that measles became much less common, likely due to increased vaccination and better public health measures

describe how stone tools and fossils can be dated to find out how old they are

by radiocarbon dating or other techniques which look at the amounts of elements like iron or potassium or comparing with other tools or fossils that have already been dated

describe the fossil evidence for human species that lived 4.4 million years ago

Ardipithecus: showing evidence of bipedalism and arboreal adaptation

how DNA can be extracted from fruit (1)

mash the fruit to break open the cells, add salt solution to break down the cell membrane and release DNA

how DNA can be extracted from fruit (2)

add detergent to dissolve the cell membrane and nuclear membrane, add alcohol to precipitate the DNA which appears as a white, stringy substance

potential applications of mapping human genomes

can help identify genes linked to diseases, assist in diagnosing genetic disorders, inform the development of targeted treatments and personalised medicine

two structural changes in a human

longer legs and larger skull

explain how natural selection can lead to the evolution of a new species

individuals produce more offspring than their environment can support, and some die because of factors such as predation, food shortage or disease

how is the growth of a baby measured

mass, length and head circumference

how is the growth of a baby measured (2)

if a baby is born on the 50^th percentile for height, then in every hundred babies, 50 will be taller and 50 will be shorter

cell cycle
interphase

the cell grows, DNA is replicated and organelles are copied

cell cycle
mitosis: prophase

chromosomes condense, nuclear membrane breaks down and spindle fibres form

cell cycle
mitosis: metaphase

chromosomes align at the equator of the cell

cell cycle
mitosis: anaphase

chromatids separate and are pulled to opposite poles

cell cycle
mitosis: telophase

new nuclear membranes form around each set of chromosomes

cell cycle
cytokinesis

the cytoplasm divides, forming two genetically identical daughter cells

how does the body protect from disease

produces antitoxins which neutralize toxins released by pathogen by binding onto it, producing antibodies which bind to the pathogen antigen, destroying it

which stage is double trial used in

clinical

what is the role of the immune system in protecting against disease

identifies and attacks pathogens using white blood cells, includes barriers, immune responses and memory cells to recognise and fight previously encountered pathogens

why did scientists conclude that statins do not cause muscle pain

the percentage of patients reporting muscle pain decreased over time in both groups, which suggests that muscle pain was likely caused by an external factor, not the statins, because the same trend occurred even without the drug

what is a double-blind trial and why is it used

in a double-blind trial, neither the patient or doctor knows who receives the real drug and who receives the placebo to prevent bias in the results and ensure the treatment’s effects are measured fairly