Additional Biology

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Give three features of a plant or algal cell which are not found in animal cells.
Cell wall, chloroplasts, permanent vacuole filled with sap.
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When, and in which direction does diffusion take place?
Happens when particles are free to move- gases, liquids (particles dissolved in solutions). Particles pass through a cell membrane to get in or out of the cell, particles move from a high to a low concentration down a concentration gradient.
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What is meant by the term 'differentiation of cells'?
When tissues grow and their cells develop to form particular cells with particular functions.
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How is a sperm cell specialised?
Tail- to swim to the egg. Middle section contains mitochondria- release energy from respiration, to move as fast as possible to egg. Acrosome- enzyme to help penetrate egg cell membrane.
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How are red blood cells adapted to carry oxygen?
Contain haemoglobin, combines with oxygen to form oxyhaemoglobin. No nucleus- more space to carry oxygen. Shape, biconcave discs- larger surface area, more oxygen absorbed efficiently. Thin outer membrane- oxygen can diffuse through easily.
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What is the function of ribosomes?
Make proteins through amino acids through protein synthesis.
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What is the function of chloroplasts?
Plants only- create food for the cell through photosynthesis, contain chlorophyll which absorb the sunlight needed.
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What is the function of mitochondria and how are they adapted for respiration?
Creates energy for the cell through aerobic respiration by breaking down glucose. Folded inner membrane, which increases surface area so as much energy can be released as possible.
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How is a bacterium cell different from a yeast cell?
Has slime capsule and no nucleus, genetic material is free in cytoplasm.
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What are the different tissues in an animal and what is their purpose?
Muscle tissue- contract to bring about movement. Glandular tissue- produce substances such as enzymes or hormones. Epithelial tissue- covers some parts of the body.
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Equation for photosynthesis.
carbon dioxide + water ----(+light energy)----glucose + oxyegn
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Why do enzymes stop working at a temp higher than 40°C ?
They become denatures, their active site changes shape and the substrate can no longer fit in.
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What is the purpose of the enzyme amylase in digestion?
It is produced in the salivary glands, pancreas and small intestine. Breaks down starch into glucose in the mouth and small intestine.
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What is the purpose of the enzyme protease in digestion?
Produced in the stomach, pancreas and small intestine. Breaks down proteins into amino acids in the stomach and small intestine.
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What is the purpose of the enzyme lipase in digestion?
Produced in the pancreas and small intestine, breaks down fats + oils into fatty acids + glycerol in the small intestine.
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What is the purpose of the enzyme pepsin in digestion?
Produced in the stomach, breaks down proteins into amino acids in the stomach.
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What are the limiting factors of photosynthesis?
Light intensity, concentration of CO2 and temperature.
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How do plants use glucose?
For respiration- to provide energy. Converted to and stored as starch, can be converted back to glucose for later use. Stored as fats and oils. Produce cellulose- strengthen plant cell walls. Make proteins.
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What is the purpose of the enzyme isomerase and why is it used in slimming foods?
Isomerase is an enzyme used to convert glucose to fructose. It is used in slimming food because it is much sweeter, so less can be used, food will have fewer calories but taste just as sweet.
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Equation for aerobic respiration.
glucose + oxygen--------carbon dioxide + water (+ energy)
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Equation for anaerobic respiration.
glucose----lactic acid (+ energy)
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Describe in detail what happens to food as it passes through he digestive system.
The insoluble food is mixed with digestive juices produced by glands, digested in stomach and small intestine. Bile produced by the liver is added to help digestion. Absorption of soluble food in small intestine. Water absorbed by large intestine.
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How do plants use glucose?
For respiration, build up smaller molecules into bigger molecules, converted into insoluble starch for storage, produce cellulose- strengthen plant cell walls, converted into fats and oils for storage- provide energy for new plant as it germinates.
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Why do plants store glucose as starch?
Glucose is soluble in water, therefore, it could affect the way water moves in and out of cells. Starch is insoluble in water, so it will have no effect on the water balance of the plant.
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How do plants use glucose from photosynthesis to make amino acids?
They combine sugars with nitrate ions and other mineral ions from the soil or water they live in. These amino acids are then built up into proteins to be used in the cells. This requires energy from respiration.
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Why does pepsin work best at about a pH of 2- very acidic?
Pepsin is found in the stomach, along with hydrochloric acid. The stomach needs these to be able to churn and break down food efficiently.
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What is the function of the bile produced by the liver in digestion?
The bile neutralises the acid from the stomach and makes the semi-digested food alkaline- provides ideal conditions for enzymes in small intestine. It also emulsifies fats, it breaks up large molecules into smaller ones to increase the surface area.
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During aerobic exercise, what changes take place in the body?
Heart rate increases, arteries supplying blood to muscles dilate (widen) to increase blood flow. Also increases the supply of oxygen and glucose to muscles, and increases the rate at which carbon dioxide is removed from muscles.
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When exercising aerobically, why can carbon dioxide be removed from the blood faster?
Breathing rate increases and you breathe more deeply, more often so you bring more air into lungs each time. More oxygen is brought into body and picked up by red blood cells, more oxygen is brought to muscles, so more carbon dioxide can be removed.
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What is an oxygen debt?
Amount of oxygen needed to break down the lactic acid to carbon dioxide and water. Heart rate and breathing rate stays high after exercise to supply extra oxygen needed to pay off oxygen debt.
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What are genes and alleles?
A gene is a small section of DNA that controls a particular characteristic. Different forms of the same gene are known as alleles.
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How many chromosomes does a body cell and a sex cell (gamete) contain?
A human body cell contains 46 chromosomes in 23 pairs, gametes contain half of this, they only have 23 chromosomes, one of each pair.
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What is mitosis?
A type of cell division where a body cell produces two identical cells, before dividing, each chromosome is duplicated in the nucleus, so when the cell divides, each new cell has a full set of chromosomes and is identical to the original cell.
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What are unspecialised cells also known as?
Stem cells
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Why does growth stop after an animal is mature?
Differentiation has already occurred in cells, they can only divide by mitosis to form the same type of cell.
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Why do plants keep growing all through their life?
Plant cells don't differentiate until in their final position in the plant, even then they can be moved form one part of the plant to another and redifferentiate to become a completely different type of cell.
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why are plants easily cloned?
They can be produced from a tiny piece of leaf tissue, where the plant cell will become unspecialised and go through mitosis many times, then they will differentiate to become a new identical plant.
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What is mitosis?
The production of gametes, a normal body cell duplicates its chromosomes, then divide, then immediately divides again. This produces 4 identical cells with half of the genetic information (not in pairs), they are not identical to the parent cell.
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why is there variation in meiosis- sexual reproduction?
Each gamete is different as they have different chromosomes, when gametes fuse- one out of each pair of genes comes from each parent. Combination of genes, will contain alleles from each parent- variation in characteristics.
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Where can stem cells be found and what are they?
An embyo is a hollow ball of cells, the inner cells of this ball are the stem cells, they can also be found in adult bone marrow. They are unspecialised cells that can differentiate into any type of cell.
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How are stem cells used to treat medical conditions?
They can be removed from embryo's and cultured to grow into different tissues, even new organs. These can then be used to treat many people such as with spinal injuries, whole new organs can be grown and used in transplant surgery.
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What are the ethical issues of culturing stem cells from embryos?
Embryos have the potential to become babies, so it is wrong to experiment or destroy them They cannot give permission, violating human rights. However, the embryos are usually spare embryos from fertility treatment, which would get destroyed anyway.
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Economical issues of of using embryonic stem cells?
Making or culturing stem cells is a very slow, difficult and expensive process. Money and research time would be better spent developing other possible treatments such as new drugs.
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What experiments did Gregor Mendel carry out, and what did he discover?
Mendel cross bred different types of peas and counted different offspring. He found that characteristics were inherited in clear and predictable patterns, some characteristics were dominant over others and they never mixed together.
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What type of genetic disorder is cystic fibrosis?
Recessive, both alleles must be inherited.
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How can polydactyly be inherited?
By inheriting only one dominant allele.
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Why is the fossil record incomplete?
Many of the very early forms of life were soft-bodied, so they have not left many traces behind.The right conditions for fossil formation were rare,and fossils have been destroyed by geological activity.
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How are fossils formed?
From hard parts of an animal that don't decay as easily, bones. Animals preserved in ice because they don't decay- right conditions not present- no oxygen, temp too low. Also when harder parts of an animal are replaced by minerals- footprint.
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What causes extinction?
New predators- prey have no adaptations to avoid them. New diseases and also other species that are more successful competitors.
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What is geographical and environmental isolation?
Geographical isolation- two populations become physically isolated by a geographical feature. Environmental isolation- climate changes in one area where one organism lives but not in others.
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Explain speciation.
When some organisms in a species have changed some much that they can no longer breed with the original species. Variety- wide range of different alleles. Successful alleles are selected that are different, changing characteristics.
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Card 2


When, and in which direction does diffusion take place?


Happens when particles are free to move- gases, liquids (particles dissolved in solutions). Particles pass through a cell membrane to get in or out of the cell, particles move from a high to a low concentration down a concentration gradient.

Card 3


What is meant by the term 'differentiation of cells'?


Preview of the front of card 3

Card 4


How is a sperm cell specialised?


Preview of the front of card 4

Card 5


How are red blood cells adapted to carry oxygen?


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