Bio

Front 1

How is Malaria spread?

Back 1

The parasite plasmodium is spread by mosquitos, vectors which dont cause the disease themseleves but spread the infection by transferring the parasite from one host to another when they feed on animals blood.

Front 2

Transmission cycle of Malaria

Back 2

1) Host already has malaria- mosquito will suck the parasite gametes into its stomach.
2) Gametes fuse and zygotes develop in mosquitos stomach.
3) Infectives stages are formed and these move to the mosquitos salivary glands.
4) when the mosquito bites another person, it injects a little saliva as an anticoagulant- contains infective stage of parasite.
5) In the human host, the infective stages enter the lover where they multiply before passing into the blood again.
6) In the blood they enter red blood cells, where gametes are produced.

Front 3

Other ways Malaria can be transmitted?

Back 3

Careless and unhygenic medical practices- unscreened blood transfusions and use of unsterillised needles can transmit the parasite.
Can also pass across placenta to unborn child.

Front 4

Global importance fo Malaria

Back 4

Kills about 3 mil people every year
Limited to areas which the mosquito can survive- currently the tropical regions but global warming could allow the mosquitos to survive further north.

Front 5

Functions of lipids in living organisms

Back 5

-source of energy- lipids can be respired to release energy to generate ATP
- energy storage- lipids are stored in adipose cells in fat stores in organisms
-all biological membranes are made from lipids
-insulation- e.g blubber in whales is lipid that reduces heat loss

Front 6

Lipids contain the elements...

Back 6

Carbon
Hydrogen
Oxygen- very low proportion

Front 7

What are reducing sugars?

Back 7

all monosaccharides and most disaccharides.
can react with another molecule by giving away electrons.

Front 8

Test for reducing sugars

Back 8

Benedict's test
add Benedicts solution (alaline copper sulfate) and heat to 80 C in a water bath.
Positive: (reducing sugars) solution changes from blue to orange-red.
The higher the concentration of sugar, the further the colour change goes. can use this to compare amount of reducing sugar in diff solutions or could filter out and weigh precipitate.

Negative: (non-reducing sugars) does not react with Benedict's solution at all so no colour change

Front 9

Primary defences

Back 9

Prevent entry of pathogenic organisms.
The skin- keratinised layer of dead skin cells acts as a barrier to pathogens
-acts as chemical barrier- produces chemicals that are antimicrobial and can lower ph, inhibit growth of pathogens

Mucous membranes: protect body openings that are exposed to the environment (mouth, ears etc). membranes secrete mucus- sticky substances that traps pathogens and contains antimicrobial enzymes

Front 10

What is an immune response?

Back 10

the bodys reaction to a foreign antigen
happens when a pathogen or parasite gets past primary defences

Front 11

What are antigens?

Back 11

molecules found on the surface of cells.
When a pathogen (eg bacterium) invades the body, the antigens on its cell surface are identified as foreign, which activates cells in the immune system

Front 12

What is a phagocyte?

Back 12

type of white blood cell that carries out phagocytosis.
found in blood and tissues
first cells to respond to a pathogen inside body

Front 13

What is phagocytosis

Back 13

engulfment of pathogens

Front 14

How do phagocytes work

Back 14

1) phagocyte recognises antigen on pathogen
2) cytoplasm of phagocytes moves around the pathogen, engulfing it
3) the pathogen is now contained in a phagocytic vacuole in the cytoplasm of the phagocyte
4) a lysosome fuses with the phagocytic vacuole and enzymes from lysosome break down pathogen
5) phagocyte sticks antigens on its surface to activate other immune system cells- T LIMPHOCYTES

Front 15

What is a T lymphocyte?

Back 15

white blood cell
surface covered with receptors

Front 16

How do T lymphocytes work?

Back 16

1) receptors bind to antigens on surface of phagocytes
2) each t lymphocyte has a different receptor on its surface
3) when a receptor on the suface of the t lymphocyte meets a complementary antigen, it binds to it
4) this activates clonal selection [
5) t lymphocyte undergoes clonal expansion- it divides to produce clones, which then differntiate into different types of t lymphocutes that carry out different functions (t helper cells, attatch to antigens on pathogen and kill cell, memory cells)

Front 17

what are B lymphocytes?

Back 17

white blood cells
covered with antibodies

Front 18

how do B lymphocytes work?

Back 18

1) antibodies bind to antigens to form an antigen-antibody complex
2) each b lymphocytes has a different shaped antibody on its surface
3) when the antibody on the surface of a b lymphocyte meets a complementary shaped antigen- it binds to it, so each b lymphocyte will bind to a different antigen
4) this + substances released from helper t cells, actives the b lymphocytes -- clonal selection
7) the activated b lymphocyte divides by mitosis into plasma cells and memory cells-- clonal expansion

Front 19

why is primary response slow?

Back 19

-when a pathogen enters bod for first time, the antigens on the surface activate the immune system.
-arent many b lymphocytes to make the antigen needed to bind to pathogen
-eventually the body will produce enough of the right antibody to overcome the infection-but shows symptoms
- after being exposed to antigen both t and b lymphocytes produce memory cells. remain in body for a long time- memory t will recognise specific antigen 2nd time, memory b will remember specific antibodies needed to bind to antigen