science: disease and defence

Question 1

infectious disease

Answer 1

categorised by pathogen (disease causing agent) into viral, bacterial, prion, protozoan and fungal diseases. infectious diseases can be spread from person to person by the transfer of pathogens in many different ways

Question 2

how does cancer affect the body

Answer 2

it is unregulated cell growth which when a cell, that has surpassed their life cycle and doesn’t/ignores the signal to die. this causes uncontrollable growth where the cell keeps replicating and dividing

Question 3

outcomes of genetic diseases (recessive vs dominant)

Answer 3

a recessive disease needs 2 faulty versions of a gene. a dominant disease only need one to be expressed

Question 4

steps to gel electrophoriesis

Answer 4

1. use enzymes from bacteria to cut DNA from specific base sequences
2. they are pipetted into wells in gel called agarose. this makes it hard for larger strands of DNA to pass through
3. placed in a buffer solution of water and dissolved ions
4. an electric current is applied to the gel. DNA is negatively changed being attracted to a positive charge.
5. smaller strands make it down the fastest.
6. the gel gets stained with ethidium bromide to see the DNA strands easier.

Question 5

explain how a gel electrophoresis separates DNA

Answer 5

as the positively charged machine is attracting negatively charged DNA strands, the smaller strands are able to get to the bottom quicker. This allows different lengths of DNA to be seen all throughout the machine, separating them from each other.

Question 6

innate defences

Answer 6

the first and second line of defence. the body naturally has defences such as hair, oil, saliva and tears to protect the outer layer of the body from getting a pathogen inside. Once the pathogen is already inside however, the body begins by with general white blood cells which eat the pathogen. They also have a fever response, where the body heats up to destroy pathogens, but this can also kill your own cells. the body also causes inflammation which is where the body makes the blood vessels leak fluid and white blood cells into the area.

Question 7

types of phagocytes

Answer 7

macrophages - the largest white blood cells
dendritic - antigen presenting cells. bring antigen material to the surface of the cell
neutrophil - eat pathogen or release chemicals to kill the pathogen
mast cell - triggers inflammation

Question 8

humoral immunity

Answer 8

with help from helper T cells, B cells differentiate into plasma B cells that produce antibodies against specific antigens. this is only if they pathogens are freely circulating.

Question 9

cellular immunity

Answer 9

inside infected cells, the body releases helper T lymphocytes which release cytokines that help activated T-cells to bind to infected cells MHC-antigen.

Question 10

antibiotics

Answer 10

antibiotics only work against bacterial infections

Question 11

aim of vaccinations

Answer 11

vaccinations aim to induce an immune response, in the individual and the population.

Question 12

herd immunity

Answer 12

vaccinations provide herd immunity as more people are vaccinated, they are less likely to get infected, causing there to be less spread.

Question 13

natural immunity: active

Answer 13

after being infected, the body’s natural response and immunity.

Question 14

artificial immunity: active

Answer 14

through vaccines, the body produces antibodies

Question 15

artificial immunity: passive

Answer 15

antibodies are injected to the body for specific pathogens

Question 16

natural immunity: passive

Answer 16

a baby getting antibodies from the mother’s breastmilk