Biology Unit 2 AQA

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What parts do human and animal cells have?
Nucleus, cytoplasm, cell membrane, mitochondria and ribosomes.
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What parts do plants have?
Cell wall, chloroplasts, permanent vacuole.
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What does a bacterial cell consist of?
Cytoplasm, membrane, cell wall. The genes are NOT in a distinct nucleus.
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What do yeast cells consist of?
Nucleus, cytoplasm, membrane, cell wall.
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Why are some cells specialised?
So they can carry out a particular function.
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How do dissolved substances move into and out of cells?
Diffusion.
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What is diffusion?
It is the spreading of the particles of a gas, or of any substance in solution, resulting in a net movement from a region where they are of a higher concentration to a region with a lower concentration.
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What makes the rate of diffusion faster?
A greater difference in concentration.
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How does oxygen required for respiration pass through a cell membrane?
By diffusion
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What are tissues?
Aggregations of similar cells with similar structure and function .
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What are organs?
Aggregations of tissues performing specific physiological functions. One organ may contain several tissues.
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What are organ systems?
When organs are organised into an organ system, which work together to form organisms.
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Give an example of a tissue.
Muscular tissue which can contract to bring about movement, glandular tissue which can produce substances such as enzymes and hormones, epithelial tissue which covers some parts of the body.
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The stomach is an organ that contains...
Muscular tissue to churn the contents, glandular tissue to produce digestive juices, epithelial tissue to cover the outside and the inside of the stomach.
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The digestive system includes...
Glands ( Pancreas, salivary glands ), the stomach and small intestine ( where digestion occurs ), the liver ( produces bile ), small intestine ( absorption of soluble food ), large intestine ( water absorbed from undigested food )
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What do plant organs include?
Stem, roots and leaves.
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What are examples of plant tissues?
Epidermal which cover the plant, mesophyll which carries out photosynthesis, exylem and phloem which transport substances around the plant.
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What do green plants and algae use to make their own food?
Light energy.
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Where do green plants and algae get the raw materials to make their food from?
The air and the soil.
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Photosynthesis is summarised by the equation...
carbon dioxide + water ( light energy ) -----> glucose and oxygen.
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During photosynthesis light energy is absorbed by a green substance called...
Chlorophyll.
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Where is chlorophyll found?
In the chloroplasts.
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Light energy is used by converting carbon dioxide ( from the air ) and water ( from the soil ) into...
Sugar ( glucose )
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The rate of photosynthesis may be limited by...
Shortage of light, low temperature and shortage of carbon dioxide.
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Glucose produced in photosynthesis may be converted into insoluble starch for...
Storage.
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Plant cells use some of the glucose produced during photosynthesis for...
Respiration.
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Some glucose in plants and algae is used to..
Produce fat or oil for storage, produce cellulose which strengthens the cell wall, produce proteins.
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How are proteins produced by plants?
Plants use nitrate ions that are absorbed from the soil.
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Physical factors that may affect organisms are...
Temperature, availability of nutrients, amount of light, availability of water, availability of oxygen and carbon dioxide.
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Quantitative data on the distribution of organisms can be obtained by...
Random sampling with quadrats, sampling along a transect.
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Protein molecules are made up of what?
Long chains of amino acids.
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Why are these long chains folded up to produce a specific shape?
So it enables other molecules to fit into the protein .
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Proteins act as..
Structural components of tissues such as muscles, hormones, antibodies and catalysts.
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What do catalysts do?
Increase the rate of chemical reactions.
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What are biological catalysts called?
Enzymes.
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What are enzymes?
Proteins
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High temperatures change what of an enzyme?
Shape.
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Different enzymes work best at different *blank* values.
pH
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The digestive enzymes are produced by what and where?
By specialised cells in glands and in the lining of the gut.
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Digestive enzymes pass out of the cells into the what, and what do they come into contact with?
Gut and food molecules.
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What is the main function of the digestive enzyme?
They catalyse the breakdown of large molecules into smaller molecules.
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Where is the enzyme amylase produced?
In the salivary glands, pancreas and small intestine.
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What do amylase do?
Catalyses the breakdown of starch into sugars in the mouth and small intestine.
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Where is the enzyme protease produced?
The stomach, the pancreas and the small intestine.
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What is the function of protease?
Catalyse the breakdown of proteins into amino acids in the stomach and the small intestine.
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Where are lipase enzymes produced?
Pancreas and small intestine.
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What is the function of lipase enzymes?
They catalyse the breakdown of lipids ( fats and oils ) into fatty acids and glycerol in the small intestine.
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Why is the stomach acidic?
Because enzymes work most effectively in these acidic conditions.
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Where is bile produced?
In the liver, but it is stored in the gall bladder before being release into the small intestine.
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What is the function of bile?
It neutralises the acid that is added to food in the stomach. This provides alkaline conditions which enzymes in the small intestine work most effectively.
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Some microorganisms produce enzymes that pass out of cells. These enzymes have many uses in home and industry. In the home, the uses are...
Biological detergents may contain protein-digesting and fat-digesting enzymes ( proteases and lipases )
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Biological detergents are more effective at * high or low * temperatures than other types of detergents.
Low
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In industry protease are used to do what in baby foods?
" Pre-digest " the protein.
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Carbohydrases are used to convert starch into what?
Sugar syrup.
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Isomerase is used to convert glucose syrup into what?
Fructose syrup which is much sweeter and therefore can be used in smaller quantities in slimming foods.
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At high temperatures enzymes are * blank * and many are costly to produce.
Denatured.
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The chemical reactions inside cells are controlled by...
Enzymes.
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During aerobic respiration chemical reactions occur that..
Use glucose and oxygen, release energy.
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Aerobic respiration takes place continuously in both...
Plants and animals.
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The reactions in aerobic respiration take place inside what?
Mitochondria.
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Aerobic respiration is summarised by the equation-
Glucose + oxygen -> carbon dioxide + water (+energy)
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Energy that is released during respiration is used by the...
Organism.
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The energy released during respiration may be used to...
Build larger molecules from smaller ones, in animals to enable muscles to contract, in mammals and birds to maintain a steady body temperature in colder surroundings, in plants to build up sugars, nitrates and other nutrients into amino acids.
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What are the changes that take place during exercise?
The heart rate increases and the rate and depth of breathing increases.
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Muscles store glucose as what?
Glycogen.
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What is used if insufficient oxygen is reaching muscles?
Anaerobic respiration to obtain energy.
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What is anaerobic respiration?
It is the incomplete breakdown of glucose and produces lactic acid.
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What do muscles become if they are subjected to long periods of vigorous activity?
Fatigued.
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What is one cause of muscle fatigue?
Build up of lactic acid in the muscles.
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What removes the lactic acid from muscles?
Blood flowing through.
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In body cells the chromosomes are normally found in what?
Pairs.
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Body cells divide by what?
Mitosis.
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The chromosomes contain what?
Genetic information.
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When a body cell divides by mitosis, what happens?
Copies of the genetic material are made, then the cell divides once to form two genetically identical body cells.
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When does mitosis occur?
During growth or to produce replacement cells.
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How many sets of chromosomes do body cells have?
2 sets
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How many sets of chromosomes do sex cells have?
One set.
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Cells in reproductive organs, testes and ovaries in humans divide to form...
Gametes
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Whats is the type of cell division in which a cell divides to form gametes?
Meiosis
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What happens when a cell divides to form gametes?
Copies of the genetic information are made, then the cell divides twice to form four gametes, each with a single set of chromosomes.
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When gametes join at fertalisation what happens?
a single body cell with new pairs of chromosomes is formed.
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Give an example of what stem cells can be differentiated into.
Nerve cells.
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Human stem cells have the ability to develop into what?
Any kind of human cell.
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Give an example of a condition which may be able to be treated by stem cells?
Paralysis
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What are the cells of the offspring produced by asexual reproduction produced by and from?
Mitosis and from parental cells.
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When gametes fuse, what comes from each parent?
Each pair of alleles
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In human body cells, what carries the genes that determine sex?
One of the 23 pairs of chromosomes.
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What is the sex chromosome for females?
(**) the same.
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What is the sex chromosome for males?
(XY) different.
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Some characteristics are controlled by what?
A single gene.
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Each gene may have different forms called what?
Alleles.
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What is it called when an allele that controls the development of a characteristic when it is present on only one of the chromosomes?
Dominant allele.
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What is it called when an allele that controls the development of a characteristic only if the dominant allele is not present?
Recessive allele.
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What are chromosomes made up of?
Large molecules of DNA
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What is a gene?
Small section of DNA.
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What does each gene code for?
A particular combination of amino acids which makes a specific protein.
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What can unique DNA be used for?
Identify individuals in a process known as DNA fingerprinting.
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What is polydactyly?
Having extra fingers or toes. Is caused by a dominant allele of a gene and can therefore be passed on by only one parent who has the disorder.
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What is cystic fibrosis?
It must be inherited by both parents. the parents may be carriers of the disorder without actually having the disorder themselves. It is cause by a recessive allele of a gene and can therefore be passed on by parents, neither of who have the disorder
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How can people look into whether embryos have these alleles?
Screening.
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Where does evidence for early forms of life come from?
Fossils.
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What are fossils?
The remains of organisms from many years ago, and are found in rocks.
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Give examples on how fossils may have been formed.
From the hard parts of animals that do not decay easily. From parts of organisms that have not decayed because one or more of the conditions needed for decay are absent. When parts of the organism are replaced by other materials as they decay.
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Give examples on why extinction may have been caused.
Changes in the environment over geological time. New predators. New diseases. New, more successful, competitors. A single catastrophic event. Through the cyclical nature of specification.
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Give reasons why new species arrive.
Isolation- two populations of a species become separated. Genetic variation - each population has a wide range of alleles that control their characteristics. Natural selection. Speciation.
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Card 4

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Card 5

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Comments

Denise

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Thanks so much :)

Alex Harrison

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Useful, comprehensive guide to AQA Biology Unit 2, though some answers are not entierly logical

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