AQA Biology paper 1 quizlet flashcards

Differences between light microscope and electron microscope

Light: are cheap to make and they allow you to see the outline of cells

Electron: Very expensive, however you can visualise finer details (including sub-cellular structures) due to higher resolution and greater resolving power

Equation for magnification

Magnification = image size / real size

Differences between Eukaryotic and prokaryotic cells

Eukaryotes have a nucleus in which their DNA is found and prokaryotic cells have no nucleus or DNA

(Plant and Animal cells)

Prokaryotes don't have a nucleus and their DNA is in loops call plasmids (Bacteria)

what does a cell membrane do and what is it

semi-permeable, controls what enters and leaves

what does a cell wall do and what is it

made of cellulose, providing rigid structure

what is cytoplasm and what happens in it

liquid that makes up the cell, where most chemical reactions take place

What does the mitochondria do?

where respiration takes place, releasing energy for the cell to function

what does chloroplasts do

contain green pigment chlorophyll, where photosynthesis takes place

what does ribosomes do

synthesises proteins

What does the vacuole do?

where cell sap and minerals are stored

difference between diploid and haploid

diploid: 23 pairs of chromosomes, 46 (human cells)

haploid: just 23 chromosomes, gametes (sperm/eggs)

what is mitosis

division of cells for growth and repair

process of mitosis

1. nucleus dissolves, genetic material is duplicated

2. two sets of chromosomes more to different sides

3. mitochondria and other organelles are duplicated

4. the cell divides producing two genetically identical diploid cells (new nuclei are formed in each)

What can stem cells do and where are they found

can specialise to perform specific functions.

found in human and animal embryos and plant meristems

what can stem cells in bone marrow be specialised into

only specialise into blood cells

advantages of stem cells

treat a wide range of diseases

disadvantages of stem cells

rejection by the body's immune system

cells can mutate e.g can turn into cancer cells

what can embryonic stem cells do

can develop into any type of body cell

ethical issues for embryonic stem cells

involves the embryo being destroyed

what's diffusion

• movement of particles from an area of high to low concentration

• down a concentration gradient

• passive: requires no energy

what's osmosis

• diffusion of water across a semi-permeable membrane

• balances the concentrations of solution in and outside a cell

what increases the rate of diffusion and osmosis

temperature, surface area, difference in concentrations

osmosis practical: potatoes

• weigh and place identical cylinders from the same potato in sugar solutions of varying concentrations

• after a set time, remove excess water and reweigh

what's active transport

• movement of particles through a membrane

via CARRIER PROTEINS

• requires energy, and so can move them against the concentration gradient

body levels organisation eg. cell…

cells > tissues > organs > organ systems

process of digestion starting with (teeth stomach liver pancreas intestines)

• teeth break down food. saliva contains amylase (enzyme)

• the stomach contains hydrochloric acid and enzymes that chemically break down food

• the liver produces bile, which breaks down lipids to form droplets, increasing their surface area

• pancreas secretes amylase, breaks down starch into glucose

• water absorbed into blood by large intestine

• nutrients (like glucose) absorbed into blood by villi in the small intestine

what are enzymes

special proteins, biological catalysts

effect of temperature and pH on enzymes

rate increases until the enzyme denatures (active site changes shape), can't work at optimum rate

what's carbohydrase

breaks down large carbohydrates into simple sugars

what's protease

breaks down proteins into amino acids

what are lipases

breaks down lipids into glycerol and fatty acids

what's starch food test

turns iodine from orange to blue-black

sugar food test

benedict's solution: turns from blue to orange

protein food test

biuret's reagent: turns from blue to purple

lipids food test

turns cold ethanol cloudy

process of respiratory system

1. air moves down trachea

2. goes into the bronchi then into the bronchioles

3. ends up in the alveoli, where air then diffuses into the blood vessels around it

4. oxygen then binds to haemoglobin in RBC and is transported around the whole body

what's alveoli

air sacks, large surface area to allow gas exchange to happen at a faster rate

Describe the double circulatory system

double circulatory system: blood enters heart twice every time it's pumped

process of the heart

1. deoxygenated blood enters through vena-cava into right atrium

2. goes through the valves into the right ventricle. muscles contract and then goes up the pulmonary artery (to lungs)

3. comes back via pulmonary vein (from lungs), goes through left atrium and ventricle, then out by the aorta

difference between right and left side of heart

right: carries deoxygenated blood, only pumps to lungs left: thicker and carrys blood all around the body so has to come with the higher pressure of blood

left: carries oxygenated blood, thicker walls due to pressure needed to pump blood to the body.

What's the artery's function and features

carries blood away from heart

• thick walls to withstand pressure

• tin lumen

veins function and features

carries blood back to the heart

• thin walls due to lower pressure

• have valves to stop back-flow

capillary features

one cell thick walls to allow fast diffusion between blood and cells.

how is CHD caused

when the artery suppling blood becomes blocked

what are stents and statins

stents: little tubes inserted into blood vessels to keep them open

statins: drugs that reduce cholesterol and fatty deposits

what are non-communicable diseases eg.

comes from inside the body, cannot spread

• cancer

• diabetes

• heart diseases (CHD)