Biology Unit 2 Revision Flash Cards Additional Science Produced by Mr P Scutt.

Biology Unit 2 Revision Flash CardsAdditional Science

Produced by Mr P Scutt


Compare the structure of animal and plant cell.


Compare the structure of animal and plant cell.

Function Animal Cell Plant Cell

Nucleus Control centre Yes Yes

Cell membrane Controls movement of materials in and out

Yes Yes

Cytoplasm Where chemical reactions occur Yes Yes

Ribosomes Site of protein synthesis Yes Yes

Mitochondria Site of respiration Yes Yes

Cell Wall Gives plants strength and rigid NO Yes

Chloroplasts Site of photosynthesis NO Yes

Vacuole Where cell sap is stored NO Yes


Describe the structure of a yeast cell and bacterium cell.


How does diffusion work?


Describe the structure of a yeast cell and bacterium cell.

Yeast Bacteria

Nucleus Yes No (DNA floats in cytoplasm).

Number of cells One/Single celled One/Single celled

Cytoplasm Yes Yes

Cell membrane Yes Yes

Cell wall Yes Yes


How does diffusion work?

Movement of molecules from a high concentration to a low concentrationDown a concentration gradient

In fluids – liquids and gases only. The bigger the difference, the faster the rate

e.g. smell across a room


Give examples of three specialised cells and their adaptations.


How are organs formed?


Give examples of three specialised cells and their adaptations.

Red Blood Cell – no nucleus (hold more Oxygen); concave shape (larger surface area for absorption).

Sperm Cell – tail with lots of mitochondria in (movement and energy to move the tail); enzymes in its head to digest the food; streamlined shape to move quicker.

Guard cell – control the opening and closing of the stomata; water in to the cells causes them to enlarge and go turgid – opening the stomata; water out of the cells causes them

to go flaccid and stomata close.

Palisade cell - lots of chloroplasts for photosynthesis; large surface area to absorb light and Carbon dioxide; thin so can pack lots in;


How are organs formed?

Cell Tissue (group of cells) organ (group of tissues) organ system (group of organs).

Glandular tissue – makes and secretes enzymes and hormones. Muscular tissue – movement

Epithelial tissue – lines the gut.


What is photosynthesis and what is needed for the process to occur?


What is meant by a limiting factor and how does is affect photosynthesis?


What is photosynthesis and what is needed for the process to occur?

Process where plants make food from water and carbon dioxideIn the chloroplasts

Chlorophyll is the pigment for trapping light.

Products are oxygen and glucose (food)


What is meant by a limiting factor and how does is affect photosynthesis?

Something that prevents photosynthesis increasing. This can beLight – needed to break up the water and carbon dioxide (the energy for the process)

Temperature – needed for enzymes to work. If too high, then enzymes will be denatured. Carbon dioxide

Water

When there is plentiful supply of everything except for one of these, then the one that is stopping photosynthesis rate increasing is called your limiting factor.


How do plants use glucose?


How can the distribution of organisms be measured?


How do plants use glucose?

For respiration – releasing energy from their food (glucose)

For making cell walls

For making proteins

For storing in seeds

For storing as starch


How can the distribution of organisms be measured?

Use a quadrat which is a square. Place randomly on an area

Count and record the number of organisms in the quadrat. Repeat over the area.

Work out the mean number of organisms in the area.

Use a transect – which is a line from a starting point, e.g. the sea, to an end point, e.g. the road.

Along the line, every 2m, record what organisms you find. Repeat the transect at a different point.


What is an enzyme and what affects how it works?


What enzymes are found in the human digestive system and how what are their products?


What is an enzyme and what affects how it works?

An enzyme is a proteinIt is a catalyst and so can speed up a reaction.

It has an active site (like a lock) which is specific to a substrate (like a key). Where only one substrate matches the shape of the active site.

When the substrate binds to the active site, a enzyme-substrate complex is formed.

It is not used up in a process. It can help to break materials down, e.g. food into smaller pieces so they can be absorbed

It is affected by temperature and pH and if there is too much of a change, then the enzyme can be denatured which means its active site changes shape.


What enzymes are found in the human digestive system and how what are their products?

Proteases – break proteins into amino acids

Lipases – break fats into fatty acids and glycerol

Amylase – breaks starch into maltose.

Maltase – breaks maltose into glucose.


Where are the human digestive enzymes found?


Describe the main parts of the human digestive system.


Where are the human digestive enzymes found?

Salivary Gland

Stomach Pancreas Small Intestine

Amylase Yes No Yes Yes

Protease No Yes Yes Yes

Lipase No No Yes Yes


Describe the main parts of the human digestive system.

Mouth – mechanical and chemical digestion by teeth and enzymes.Down oesophagus

Into stomach – churns (muscular walls), combines with acid (kills bacteria and breaks down food), pepsin enzyme breaks down proteins

Bile (made in liver, stored in gall bladder) released to neutralise the stomach acid. Bile also emulsifies fats.

Small intestine – food absorbed via villi into blood stream. All enzymes found here to break down food so small enough to diffuse into blood.

Large intestine – water reabsorbedRectum – store faeces.


Compare the different types of respiration.


Where are enzymes used in industry and around the home?


Compare the different types of respiration.

Respiration is the breaking down of food to release energy.Occurs in the mitochondria.

Aerobic – involves oxygen and produces carbon dioxide and water

Anaerobic – no oxygen – produces lactic acid which leads to cramp if exercising. Does not produce as much energy as aerobic. Used when exercising very hard.


Where are enzymes used in industry and around the home?

Biological detergents – washing powders so they can break down food substances at lower temperatures. Therefore, cheaper to wash clothes as don’t have to heat water as

high.

Baby food – add protease to break down food before baby eats them so increase chance of absorbing them.

Make food sweeter by changing the sugar to fructose so need less of it – good for slimming purposes.


Describe what DNA, genes, chromosomes and inheritance is/are.


What are the main steps in mitosis?


Describe what DNA, genes, chromosomes and inheritance is/are.

DNA is a double helix (spiral) which contains genesDNA for chromosomes

Genes are small sections of DNA that code for amino acids (20 different ones). These amino acids form proteins.

Found in the nucleus

Genes are passed on from one generation to the next – inherited.

Everyone has different DNA and so can be used for genetic fingerprinting/paternity testing.


What are the main steps in mitosis?

Chromosomes replicate and condense (i.e. copy itself and get smaller) – form X shape

Chromosomes line up at equator (centre of the cell)

Spindle fibres attach to each side of the chromosome These pull the chromosome apart towards the two poles at opposite ends of the cell.

The cell divides in to two

They are exact copies of the original cellUsed for growth and repair

This is an example of asexual reproduction


What are the main steps in meiosis?


What are stem cells and how can they be used?


What are the main steps in meiosis?

Chromosomes replicate and condense (i.e. copy itself and get smaller) – form X shape

Chromosomes line up IN PAIRS at equator (centre of the cell)

Spindle fibres attach to each chromosome These pull the chromosome apart towards the two poles at opposite ends of the cell.

The cell divides in to two

A SECOND division occurs OF BOTH CELLS, where the chromosomes line up at equator (centre of the cell)

Spindle fibres attach to each side of the chromosome These pull the chromosome apart towards the two poles at opposite ends of the cell.

The cell divides in to two (forming four cells in total)

They are gentically different from the original cellUsed to form the gametes (sex cells – sperm and egg)

This is an example of sexual reproduction


What are stem cells and how can they be used?

Embryotic cells can turn into ANY cell.

Differentiation is where a cell changes into a specific cell.

Plant cells never lose this ability, unlike animal cells.

Found in bone marrow in animals

Can be used to cure diseases – bone marrow transplants for people with blood diseases. Replace faulty cells – heart disease, insulin-producing cells,


How is gender determined by your genes?


Describe the part of Mendel in what we now know about genetics.


How is gender determined by your genes?

One pair of chromosomes determines genderXX – femaleXy – male

You get one chromosome from each parent. There is a 50% of offspring being male or female

X X

X XX XX

Y XY XY


Describe the part of Mendel in what we now know about genetics.

He tested pea plants and reproduced them in different waysHe found that genes have two types

Dominant allele (different version of same gene) – ones that overrule another geneRecessive allele – ones that are over ruled by dominant genes, but when two recessive

genes are together the characteristic is expressed.

Eg. BB – Brown eyes; Bb – Brown eyes;

bb – blue eyes


Show how inheritance of eye colour is determined using a genetic cross.


Give some examples of genetic disorders and how they are caused.


Show how inheritance of eye colour is determined using a genetic cross.

B – Dominant brown alleleb – recessive blue allele

Dad has BB genotypeMum has bb genotype

All offspring are ‘Bb’ and so have brown eyes.

B B

b Bb Bb

b Bb Bb


Give some examples of genetic disorders and how they are caused.

Cystic Fibrosis – caused by recessive alleleCells produce a sticky mucus in the air ways and in the pancreas

1:4 chance of having if both parents are carriers

Polydactlyl – caused by the dominant alleleBorn with extra fingers or toes.

Non-life threatening50% chance if one parent has it.

Biology Unit 2 Revision Flash Cards Additional Science Produced by Mr P Scutt.

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