Biology Unit 2

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  • Created by: elliesp
  • Created on: 24-04-16 10:28
what are the 4 different types of cell?
animal, plant, bacterial, yeast
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which cell doesn't have a cell wall? what do they have instead?
animal cell, they have cell membrane instead
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what are the features of an animal cell?
nucleus, cell membrane, mitochondria, cytoplasm, ribosomes
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what are the features of plant cells?
vacuole, chloroplasts, cell membrane, cell wall, nucleus, cytoplasm, ribsomes, mitochondria
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what are the features of bacteria?
cell wall, cell membrane, small ribosome, plasmid, genetic material
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what are the features of yeast?
nucleus, vacuole, vacuole membrane, mitochondrion, cell wall, cell membrane, lipid.
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what is the function of a nucleus?
a nucleus is the control centre of the cell, it controls all cell activity and contains DNA
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what does the cytoplasm do?
a jelly like substance where all chemical reactions happen
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what does the cell membrane do?
the cell membrane controls what enters and leaves the cell
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what does a ribosome do?
makes proteins from amino acids
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what do mitochondria do?
produce energy from respiration
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what do chloroplasts do?
contain chlorophyll to absorb sunlight needed for photosynthesis
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what does a vacuole do?
a space filled with sap to inflate the cell
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what does a cell wall do?
a rigid outer layer to provide strength and support
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what do lipids do?
store energy
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what is diffusion?
diffusion is the movement of particles from an area if high concentration to an area of low concentration until they're evenly spread
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explain diffusion in the blood
blood capillaries in lungs take in oxygen from aveolus (where there is a higher concentration of oxygen). Oxygen diffuses across alveolar walls into capillaries & to red blood cells. Co2 diffuses from blood to the alveolus (low concentration of co2)
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explain diffusion in liquids and gases
When particles are concentrated in only one part of a region, they will move around randomly until they’re evenly spread through the whole region and are less concentrated.
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what are the limitations of fusion?
can be slow, stops when substances are evenly spread so can only ever exchange half,
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what do plants use glucose for?
for respiration to release energy, to make compounds such as starch, cellulose, lipids and protein.
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explain diffusion in animal cells
in animal cells oxygen is required for respiration so oxygen is diffused from an area of high con. outside cell, into an area of lower con. inside cell. Also, h20 is diffused from area of high con. inside cell to area of high con. outside cell.
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explain diffusion in plant cells
co2 needed for respiration in plant cells, so is diffused from an area of high con. outside cell to area of low con inside. BUT, oxygen is made by photosynthesis so oxygen is diffused from area of high con. inside cell to area of low con. outside.
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what is the actual purpose of diffusion?
so substances can cross cell membranes
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how can the rate of diffusion be increased?
by increasing the difference in concentration, by reducing distance between them, by increasing surface area.
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what processes of diffusion have been evolved to overcome limitations of diffusion?
FACILITATED: diffusion sped up by special proteins in the membrane, ACTIVE TRANSPORT: where substances can be exchanged beyond equilibrium
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what do specialised cells do?
form tissue
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name 4 specialised cells
sperm cells, nerve cells, root hair cells, red blood cells
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what are the features of sperm cells
head contains DNA, tail to swim to egg, a lot of mitochondria to provide energy from respiration for swimming
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what is the purpose of a nerve cell?
are long to transmit nerve impulses from one part of the body to another
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what are the features of a root hair cell?
a large surface area so can absorb more water and minerals, has no chloroplasts as under the skin they don't need to absorb light
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what are the features of red blood cells?
contain haemoglobin, which carries oxygen. Has no nucleus so it has more space to carry oxygen. Large surface area to carry more oxygen.
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what is tissue?
a tissue is a collection of cells with similar structure and function
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examples of tissues? what do they do?
Muscle tissue: function to contract, Glandular tissue: makes and secretes substances such as mucus, enzymes and hormones, Epithelial tissue: forms thin flat sheets that act as covering for many parts of the body.
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what are organs?
made up of tissue, a structure in the body that has a specific function
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what do organs form?
organs form systems which join to complete a major function in the body
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what does the circulatory system do?
carries oxygen and nutrients to cells via blood and removes waste products
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what is the respiratory system?
the respiratory system supplies oxygen to blood so blood can deliver oxygen to all parts of body
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what is the main function of digestive system
breaks down large molecules into smaller soluble molecules so they can be absorbed
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what is the function of the nervous system
a network of specialised cells communicating info about stimuli and providing a response to them
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what does the digestive system include?
glands (stomach,pancreas &salivary glands), small intestine, large intestine, liver
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what are the glands?what do they do?
pancreas, stomach, salaviry glands= produce various gastric juices
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what does the stomach do?
Prior to going to the small intestine, the stomach breaks down food with its digestive juices (hydrochloric acid) and breaks it down by churning it.
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what does the liver do?
the liver produces bile (an alkali digestive fluid) which neutralises the acidic food coming out of the stomach
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what does the small intestine do?
Absorbs small food particles through micro villi. These nutrients then go through the veins and are carried through the body by blood.
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what does the large intestine do?
where water is absorbed from undigested food, producing faeces.
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what does the pancreas do?
it is a gland that produces enzymes and hormones
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name the types of tissue in a plant?
epidermal, mesophyll, xylem and pholem
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what are epidermal tissues?
they cover most of the plant
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what are mesophyll tissues? and where are they found?
mesophyll tissues are found in the centre of leaves and carry out photosynthesis
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what are the most important cells in mesophyll tissue? why?
palisade cells as they carry out most of the plants photosynthesis as they contain lost of chloroplasts
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what do xylem and phloem tissue do?
xylem and phloem transport substances around the plant and are made of long tubular cells
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what do xylem vessels do?
take water and dissolved minerals from the roots to upper parts of the plant, such as the leaves
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what do phloem vessels do?
take products of photosynthesis (mainly glucose) and transport them from the leaves where they're made to where they're needed around the rest of the plant.
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why do leaves have veins? also why are they thin?
leaves have veins to transport water and carbohydrates and to support them. They are thin so that there is only ashore distance for co2 to diffuse into the leaf and so the rate of diffusion is quicker
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what is photosynthesis?
photosynthesis is the chemical change in the leaves of green plants where glucose is made from carbon dioxide, water and light.
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explain how photosynthesis happens
co2 absorbed by leaves from air and water absorbed through roots which travels up stem into leaf. In palisade layer, chloroplasts absorb sunlight which helps the co2 in leaves react with water to make glucose. oxygen made as by-product.
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how can you tell a plant has been photosynthesising?
starch produced in the leaves so a starch test is carried out using iodine. if starch is present it will turn blue/black. the left must be boiled in water first and heated in iodine so that all chemical reactions are stopped and all colour is removed
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what is the formula for photosynthesis?
carbon dioxide + water --> glucose + oxygen
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what are the limiting factors of photosynthesis?
light intensity (not enough light, not enough energy to activate chlorophyll), co2 conc. (not enough co2, not enough raw material to make glucose), temp (effects enzymes in plant, if not at optimum temp slows growth and rate of photosynthesis)
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what is needed to make proteins in plants?
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what is needed to make DNA in plants?
nitrate and phosphate
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what are abiotic factors?
non living things
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what are biotic factors?
living things
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what are the abiotic factors of distribution of a species?
temp, light, water, co2, nutrients
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what are the biotic factors of the distribution of a species?
availability of prey, predators, competition, disease
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what are enzymes?
a type of protein used as biological catalysts
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what are proteins made of?
amino acids
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list some types of proteins?
insulin, enzymes, antigens, fibres in muscle, keratin, collagen
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what does collagen do?
collagen gives strength to bones and makes tendons stronger
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what does keratin do?
keratin makes hair nails and hooves stronger
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describe how enzymes break things down?
enzymes are make of long chains of amino acids which each make different shapes. each enzyme will only fit one substrate ( a type of molecule), & can react with that substrate & break it down. The shape which the substrate fits in is the active site
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describe how temp effects enzymes?
if temp too cold, enzymes don't react quickly s don't have enough energy. If enzymes too hot will be denatured & won't fit substrate & won't react. enzymes at optimum temp at 35 degrees,have lot of energy,collide w substrates frequently,react quickly
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how do enzymes help in digestion? (in digestive system)
large molecules too big to pass through intestine wall into blood, specialised cells in gut lining release enzymes to break down food into small soluble molecules in gut. as food passes along gut, digested molecules absorbed into blood.
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how is starch broken down?
starch is broken down into sugars/glucose by an enzyme called amylase
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How is protein broken down?
protein is broken down by an enzyme called protease, first it is borkne into short chain amino acids and then into individual amino acids
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what are lipids?
fats and oils
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how are lipids broken down?
lipids are broken down into fatty acids and glycerol by an enzyme called lipase
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how are enzymes used in industry?
manufacturers add protease to baby food to break down proteins in it, so easier for babies to digest. Glucose can be made by adding starch to carbohydrates called amylase and maltase. Fructose made by adding isomerase to glucose
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how are enzymes used at home?
protease used to break down protein stains, lipase used to break down fat/oil stains in biological detergents.
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what affects the speed of enzyme activity?
amount of enzymes, amount of substrates, temp, pH
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3 parts of digestive system that produce amylase?
salivary gland, pancreas, intestine wall?
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2 parts of digestive system that produce lipase?
pancreas, intestine wall
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3 parts of digestive system that produce protease?
stomach, pancreas, intestine wall
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what are advantages of using enzymes in industry?
can be reused, speed up reactions as they are biological catalysts so lots of expensive equipment doesn't have to be used to provide a lot of energy.
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what are disadvs of enzymes in industry?
each enzymes only works on one substrate, can be costly to get the right enzyme, only work in specific temp and pH conditions.
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advs and disadvs of using enzymes in washing detergent?
Advantage — effective at low temperatures, which saves money on fuel. Disadvantage — enzymes are specific (may not remove all stains)
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what is respiration?
Respiration is a chemical reaction that happens in all living cells. It is the way that energy is released from glucose, for our cells to use to keep us functioning.
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what is aerobic respiration?
Aerobic respiration is the form of respiration which uses oxygen.
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what is anaerobic respiration?
form of respiration without oxygen/ incomplete break down of glucose. Some energy is released from glucose by anaerobic respiration, but oxygen is needed to get all energy out. Incomplete combustion of glucose produces lactic acid.
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word equation for aerobic respiration?
glucose + oxygen --> carbon dioxide and water (+energy)
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word equation for anaerobic respiration?
glucose --> lactate and energy
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what are the uses of the energy made from respiration?
to produce heat and maintain a perfect body temp, to contract muscles, to build up chains of amino acids to make proteins which help growth
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what happens when muscles are working hard? (what is used up and produced)
a lot of glucose and oxygen is used up and a lot of co2 and heat produced
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how does the body react to raised co2 levels?
increases heart rate, increases ventilation rate. this means that as more oxygen and glucose is being delivered around the body (through blood and breathing) which gets rid of excess co2 and heat
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what is glycogen? where is it stored?
substance made of glucose molecules bonded together, provides a lot of energy. stored in liver and muscles.
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what can we do when we're short on glucose?
break down glycogen to get glucose.
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what happens when there is a build up of lactic acid in your muscles? what does this mean in terms of the amount of exercise you can do?
your muscles fatigue and stop contracting efficiently, therefore you can't continue exercising at full speed for a long time.
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how do you remove lactic acid?
heart rate increases to get rid of lactic acid in muscles by glucose and oxygen in blood. then lactic acid must be removed from blood so breathing rate increases, and adding oxygen to lactic acid turns it into co2 and water.
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how many chromosomes do humans have?
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how are chromosomes formed?
strands of DNA from nucleus of body cell are copied so two identical strands roll up into x shapes.
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how many chromosomes does a body cell have?
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how many chromosomes does a sex cell have?
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what is mitosis?
mitosis is the division of body cells.
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what is meiosis?
meiosis is the division of sex cells
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explain mitosis.
firstly the chromosomes in the cell are copied (amount goes from 46 to 92), then half of the chromosomes move to each end and the cell divides.
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why is mitosis used?
for repair, growth or replacement of cells. Also, used in asexual reproduction.
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explain meiosis?
the original sex cell has 46 chromosomes and double it's amount so it has 92, then the cell divides twice to produce 4 new cells (each with 23 chromosomes). BUT during meiosis genes are shuffled so each cell is different.
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how many divisions happen in mitosis? how many in meiosis?
1 in mitosis, 2 in meoisis.
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what are stem cells?
stem cells are unspecialised cells that have the potential to become nay other cell in the body
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what can spare embryonic stem cells from IVF be used for?
to repair spnial injuries, to replace organs (transplant)
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why is using stem cells from IVF controversial?
could've been a potential human, no right to interfere with natural processes - HOWEVER: saves lives and cures diseases.
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what is a gene?
a short piece of DNA that codes for making a particular protein
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what is an allele?
a specific form of gene
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what is a phenotype?
observable features of an organism
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what is a genotype?
coding of genes (e.g rR, rr, RR)
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what is DNA fingerprinting used for?
paternity tests, criminal identification.
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what is polydactyly?
polydactyly is when a person is born with extra toes or fingers
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what coding does a polydactyly allele have?
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what is cystic fibrosis?
a genetic disorder causing mucus build up in lungs
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what can cystic fibrosis effect?
digestion, breathing, stops oxygen getting to blood causing infection
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what coding is cystic fibrosis?
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what is embryo screening?
a way of checking whether an embryo carries alleles for certain diseases
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explain the process of embryo screening
egg cell and sperm cell fertilised outside body (IVF), allowing them to become embryos, cells taken from embryos to check whether they have the alleles. unaffected ones can be placed back into uterus.
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how are fossils formed?
if dead organism in conditions where no oxygen,cold,no moisture& highly acidic - not likely to decay as decomposers don't work well.So tissue preserved & compressed by layers of sediment over years.Eventually tissue replaced by rock in mineralisation
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which cell doesn't have a cell wall? what do they have instead?


animal cell, they have cell membrane instead

Card 3


what are the features of an animal cell?


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Card 4


what are the features of plant cells?


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Card 5


what are the features of bacteria?


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