GCSE AQA biology PAPER 1 Higher

Are animal cells eukaryotic or prokaryotic?

Eukaryotic

Are plant cells eukaryotic or prokaryotic?

Eukaryotic

Are bacteria cells prokaryotic or eukaryotic?

Prokaryotic

are prokaryotic cells much bigger or smaller than eukaryotic?

much smaller

Parts of a eukaryotic cell

cell membrane, cytoplasm, nucleus

Parts of a prokaryotic cell

cell wall
dna loop
cell membrane
cytoplasm
plasmids

give 5 sub cellular structures that are found in both animal and plant cells?

-nucleus
-cytoplasm
-cell membrane
-ribosomes
-mitochondria

give 3 sub cellular structures that are found in plant cells but not in animal plants?

-cell wall
-chloroplasts
-permanent vacuole

what the function of the nucleus ?

contains genetic material

Function of cell membrane

regulates what enters and leaves the cell

function of mitochondria

cellular respiration

function of chloroplast

Contains chlorophyll which absorbs light energy for photosyntheis

cell wall function?

provides support and protection

function of plasmids in bacteria cell?

contains extra genetic material that can help the bacteria cell survive

What are plant cell walls made of?

cellulose

what is a plant cells permanent vacuole filled will?

cell sap

give 2 differences between electron microscopes and light microscopes?

electron microscopes have a much higher magnification and a much higher resolution than light microscopes

what formula is used to calculate magnification of an image?

magnification = imagine size /real size

give a brief method for using a light microscope to look at a prepared slide

USING A LIGHT MICROSCOPE TO LOOK AT A PREPARED SLIDE
1)put the slide on the stage
2)select the lowest power lens
3)use the coarse adjustment knob to roughly focus the slide
4)use the fine adjustment(FA)knob to clearly focus the slide
5)switch to a higher power lens to increase magnification and refocus with the FA knob

give 3 things to remember when drawing cells observed through a light microscope ?

-use a pencil
-label the main structures
-include the magnification used

what happens when cells differentiate?

when cells differentiate they develop different sub-cellular structures that make them carry out certain functions

how are animal cells different to plant cells in their ability to differentiate?

most animal cells differentiate early in development and can't differentiate again

many plant cells can differentiate whenever they need to

give 3 ways that a sperm cell is specialised to do its job

:to get DNA into egg cell
-tail for swimming
-lots of mitochondria to provide energy
-enzymes in head to digest egg cell membrane

give 2 ways that a nerve cell is specialised to do its job

FUNCTION:carries messages around the body at high speed
-fatty sheath speeds up message transport
-long so it can carry messages over a distance

how is a plant root cell specialised to do its job?

FUNCTION:helps a plant absorb water and minerals from soil.
-a long and thin extension gives a larger surface area for absorption

give 2 ways that muscle cells are specialised to do their jobs?

FUNCTION:creates movement by contracting and relaxing
-long protein strands that can slide over each other ti shorten/lengthen the cell
-lots of mitochondria to generate energy

How are xylem cells specialised?

FUNCTION:Xylem cells form tubes that transport ester and minerals through the plant.
*they're dead cells with holes at either end-water and minerals can just flow right through them

How are phloem cells specialised?

FUNCTION:transport dissolved sugars in a plant.
-few sub cellular structures so sugars flow through easily
-pores in end walls to let sugars through

Where are chromosomes found?

nucleus

what are chromosomes made up of?

long lengths of DNA

how many chromosomes are there in the total human body?

there are 46 in a human body cell

how many pairs of chromosomes are there in the human body cell?

there are 23 pairs of chromosomes in a human body cell

why is the cell cycle important?

because it creates new cells which allows organisms to grow and develop

what are the three stages of the cell cycle?

1)growth
2)mitosis
3)Division

what happens during the growth stage of the cell cycle?

-extra sub cellular structures are made
-the DNA of each chromosome is duplicated

what happens during mitosis in the cell cycle?

-chromosomes are pulled apart to opposite ends of the cell
-nucleus from around each set of chromsomes

what happens during division stage of the cell cycle?

-the cytoplasm and cell membrane split into two
-two cells form that are genetically identical to each other and the original cell

what is a stem cell?

an undifferentiated cell that can divide to make more stem cells or differentiate into certain types of cells

whats the difference between stem cells from human embryos and stem cells from adults?

human embryos can differentiate into most types of cells.

stem cells from adults can only differentiate into certain cell types

give 2 conditions stem cells could treat

-Diabetes
-paralysis

describe how therapeutic cloning works?

TC is a treatment where an embryo is made with the same genes as a patient.

Stem cells from the embryo are used to treat the patient-the stem cells aren't rejected because they are genetically identical to the patients other cells.

give a risk of using stem cells to treat illnesses

-stem cells can become infected with viruses

using infected stem cells to teat a patient risks transferring a viral infection to the patients

why do some people object to the use of stem cells from human embryos?

Human embryos are destroyed when stem cells are collected from them.

As embryos could become human beings, some people believe destroying embryos is like killing a human being.

where are stem cells found in plants?

Meristems in roots and stems

when during a plant's life can its stem cells differentiate?

they can differentiate right throughout the plants life

plants can be cloned quickly and cheaply

give 2 things that are made possible by this

-Protect rare plant species from extinction

-produce large numbers of identical crops with features like disease resistance

what Is diffusion?

the spreading out of particles in a solution or gas from an area of higher concentration to an area of lower concentration

How is the rate of diffusion affected by temp?

the rate increases as temp increases

how does the rate of diffusion affect the size of the concentration gradient?

rate increases as the size of the concentration gradient increases

how does the surface area of the cell membrane affect rate of diffusion in and out of the cell?

rate increases as the surface area of the cell membrane increases

give 2 examples of substances transported by diffusion in the body

-oxygen and carbon dioxide diffuse between blood and the lungs (gas exchange)
-urea diffuses from cells into blood plasma

what is osmosis?

the diffusion of water molecules from a dilute solution to a concentrated solution through a partially permeable membrane.

outline how the effect of different concentrations of salt solution on plant tissue can be investigated?

by comparing the change in mass of potatoes cylinders after leaving them in different concentrations of salt solutions for the same time.
(if a potato cylinder is left a salt solution with a higher concentration of water than in potatoes cells, the cylinder draws in water by osmosis and gets heavier)

give a brief method for investigating the effect of different concentrations of salt solutions on plant tissue

1)cut identical potatoes cylinders and record their mass
2)fill boiling tubes with a range of concentration of salt solution e.g0-1 mol/dm^3
3)put cylinder in each tube
4)after 24 hours, remove and dry the cylinders, then record their masses again.

What is active transport?

the movement of substances from a more dilute solution to a more concentrated solution

Why does active transport require energy?

it moves substances against a concentration gradient

where does the energy required for active transport come from?

respiration.

why do plant root hair cells use active transport to absorb mineral ions from soil?

the concentration of mineral ions in soil is normally lower than the concentration of mineral ions in plant root hair cells.

this means that ions can't just diffuse in-so plant root hair cells use active transport to absorb mineral ions from soil

When is active transport used in the gut?

When there is a lower concentration of nutrients in the gut but a higher concentration of nutrients in the blood

how do u calculate surface area to volume ratio?

1)calculate the area of each surface and add them together
2)calculate volume
3)show as simplified ratio of total surface area to volume

whats an exchange surface?

a specialised area of an organism that efficiently transfers substances between the organism and its environment

why don't single celled organisms need exchange surfaces ?

single celled organisms have relatively large surface area to volume ratio.

this means substances can diffuse over their cell membranes at. rate thats high enough to keep them alive.

this means single celled organisms don't need exchange surfaces

why do multicellular organisms need exchange surfaces?

multicellular organisms have relatively small surface are to volume ratio .

substances can't diffuse over their surfaces at a level thats high enough to keep all of their cells alive.

this means that multi cellular organism need exchange surfaces to transfer substances efficiently.

give 4 adaptations of exchange surfaces to increase they effectiveness

-Large surface area(lets more substances diffuse at once)
-Thin membrane (speeds up diffusion because diffusion distance is short)
-Rich blood supply in animals.(takes things to and from exchange surface efficiently )
-gas exchange surfaces are exposed to the air(in animals)

give 3 ways that the small intestine is adapted for exchanging surfaces

-walls are folded and have millions of projections called Villi to give a massive surface area
-Villi have very thin walls
-Villi have a rich blood supply

give 3 ways that alveoli in the lungs are adapted for gas exchange

-thin walls
-a rich blood supply
-large surface area

give 2 ways that plant leaves are adapted for gas exchange

-opening in epidermal tissue called stomata let gases in and out of the leaf
-air spaces inside leaf tissues allow gases to diffuse in and out of cells

how does the structure of fish gills help it exchange gases with water

A fishes gills are made up of lots of gill filaments, which are covered in lots of folds called lamellae

this gives the gills a large surface area, which increases rate of diffusion of gases between the fish's blood and water

give 3 ways that the lamellae in a fish's gills are adapted for exchanging gases with water

-thin walls
-a rich blood supply
-blood flows through them in the opposite direction to water flowing over them

what is a tissue?

A group of cells that act together to perform a specific function.

what Is an organ

A group of different tissues that work together to perform a certain function.

what is an organ system?

A group of organs working together to perform a particular function

put these in order (smallest to largest):organ, tissue, organ system, cell

1)Cell
2)Tissue
3)organ
4)Organ system

wha are enzymes?

proteins that catalyse chemical reactions in an organism

whats an enzymes active site?

the part of an enzyme that a substrate blinds with

why do enzymes only catalyse specific reactions?

an enzymes active site is a specific shape

Only certain substrates fit the active, so an enzyme can only catalyse specific reactions

describe the lock and key model of enzyme action

Only a substrate that exactly fits an enzymes active site can bind to the enzyme.

once a substrate binds, the enzyme catalyse the reaction

what does it mean when an enzyme is denatured?

When an enzyme is denatured, its active site changes shape.

This means the substrates won't fit the active site any more, so the enzyme can't catalyse any more reactions.

how does changing temp affect the rate of a enzyme catalysed reaction?

as temp increases, the rate of enzyme catalysed reaction increases.

But of the temp gets too high enzymes get denatured and the rate of reaction decreases.

Enzyme's optimum pH and temp, what's it meant by this?

The PH and temp at which an enzyme works best are the enzymes optimum temp and PH

Give the two things that causes enzymes to denature

-High temperatures
a ph value thats too high to too low

outline how the effect or PH on amylase activity can be investigated

the effect of PH on amylase activity can be investigated by comparing how long it takes amylase to fully break down a sample of starch solution at different PH levels

Give a brief method for investigating the effector PH on amylase activity

1)Put a drop of iodine solution in each well of a spotting tile
2)Add 2cm^3 starch solution and add 2cm^3 of PH5 buffer solution to a test tube in a water bath at 35*C
3)After 10 mins, stir in 2cm^3 of amylase solution and start timing
4)Take a drop from the test tube every 20 seconds and put it in well- repeat until the iodine solution stays orangey and record the time passed.
5)Repeat the experiment with a range of PH buffer solutions

Organs of the digestive system

Salivary glands,Oesophagus,Stomach,Liver,Gall blader,Pancreas,Small intestine and large intestine

what do digestive enzymes do?

break down big molecules into smaller ones that will be absorbed into the blood

What are carboghydrases

Digestive enzyme that catalyse the break down of carbohydrates into simple sugars

what does amylase catalyse?

Amylase catalyses the breakdown of starch into simple sugars

give 2 places in the body where amylase is produced

-Salivary glands
-Pancreas

What do proteases catalyse?

Proteases catalyse the breakdown of proteins into Amino acids

give 2 places in the body where proteases are produced

-stomach
-pancreas

what do lipase catalyse?

lipases catalyse the breakdown of lipids into fatty acids by glycerol

give 3 places in the body where lipase are produced

-mouth
-stomach
-pancreas

where is bile produced and where is it stored?

produced in the liver and stored in the gallbladder

Bile is an alkaline substance
Explain why this is important for digestion

During digestion, food that's mixed with hydrochloric acid passes from the stomach into the small intestine.

Bile is an alkaline substance that neutralises the acid so the digestive enzymes in the small intestine can function at their optimum PH

Bile emulsifies fats
what does this mean and why is it important for digestion?

This means it turns fat into very small droplets.

This creates a large surface area for lipase to act on, increasing the rate of lipid breakdown by lipase

Describe how to test a food sample for sugars

1)Heat a water bath to 80*C
2)Put the food sample in a test tube and add a few drops of Benedict's solution
3)Put the test tube in the water bath for around 5 minutes
4)if sugars are present, the solution changes from blue to green(some sugar),yellow or brick-red (lots of sugar)

Describe how to test a food sample for starch

1)put the food sample in a test tube
2)Add a few drops of iodine solution to the test tube
3)if starch is present, the solution changes from orangey to blue-black.

Describe how to test a food sample for protein

1)put the food sample in a test tube
2)Add 2cm^3 of biuret solution
3)Gently shake the test tube
4)if protein is present, the solution changes from blue to violet or purple

Describe how to test a food sample for lipids

1)Put the sample in
a test tube with some distilled water
2)Add a few drops of ethanol OR a few drops of Sudan III stain to the test tube
3)Gently shake the test tube
4)if lipids are present, a cloudy emulsion forms(ethanol)OR a separate red layer forms at the top (Sudan III stain)

parts of the lung

Trachea, lung, bronchus, bronchioles and alveoli