Biology 2b flashcards

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  • Created by: Evie
  • Created on: 20-04-13 14:20
What are enzymes and what are they made of?
They are biological catalysts which speed up useful chemical reactions. They are proteins which are made up of long amino acid chains.
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Define a catalyst
A substance which increases the speed of a reaction, without being changed or used up in the reaction.
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What happens when an enzyme becomes denatured?
Some of the bonds holding the enzyme together start to break, destroying the shape thus the substrate can't fit
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What would happen if you increase the substrate concentration in a reaction?
The reaction will become faster and then level off until all the enzymes are working at their maximum rate. At this point increasing it more won't do anything.
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What do enzymes do in the digestive system?
They break down big molecules into small molecules
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What enzyme turns starch into sugar? Where is it made?
Amylase. Made in the salivary glands, small intestine and pancreas.
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What does protease do and where is it made?
Proteins into amino acids. Made in stomach (its called pepsin there), pancreas and small intestine
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What does lipase do and where is it made?
Lipids into glycerol and fatty acids. Made in small intestine and pancreas.
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What does bile do? Where is it produced?
Bile neutralises the stomach acid. The HCl in the stomach makes it too acidic for enzymes in the small intestine to work. It also emulsifies fats (making them into droplets=larger surface area=faster enzymes. Produced in liver, stored in gall bladder
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What is the function of the large and small intestine?
Large- absorbs excess water from the food. Small- produces amylase, protease & lipase + where digested food is absorbed into the blood
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What are 3 functions of the stomach?
Pummels food with muscular walls, produces protease/pepsin, produces HCl to kill bacteria and give the right pH for protease
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Define respiration
The process of releasing energy from glucose which happens in every cell.
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What is the reaction for aerobic respiration? Define it.
Glucose+oxygen = CO2+water+ ENERGY. Respiration using oxygen.
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4 things energy released by aerobic respiration is used for?
Building up large molecules from small ones. In animals, allowing muscles to contract/move. In mammals and birds to keep body temperatures steady. In plants to build sugars, nitrates and other nutrients into amino acids.
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What does an increase of muscle activity require?
More glucose and oxygen to be supplied to the muscle cells. Extra CO2 needs to be removed from them, thus blood has to flow at a faster rate.
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What does physical activity do?
Increases your breathing rate and makes you breath more deeply for the need for extra oxygen. Increases your heart rate.
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What is glycogen? Why do we use it?
Some glucose from food is stored as glycogen, mainly in the liver but each muscle has its own supply. During vigorous exercise muscles use glucose rapidly, so some stored glycogen is converted back into glucose for more energy.
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What is the reaction for anaerobic respiration? Define it.
Glucose = energy + lactic acid. Its respiration without oxygen, the incomplete breakdown of glucose which produces lactic acid.
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What is muscle fatigue?
Where muscles get tired and stop contracting effectively.
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Pro and con of anaerobic exercise?
Con- doesn't release as much energy. Pro- you can keep on using your muscles for longer
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What is oxygen debt?
After resorting to anaerobic exercise, when you stop exercising you'll have to repay the oxygen that you didn't get into your muscles in time. So you breath hard to get oxygen into your blood which flows through your muscles to remove the lactic aci
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What are the effects of it?
You breath hard to get oxygen into your blood which flows through your muscles to remove the lactic acid by oxidising it into CO2 and water. The pulse and breathing rate stay high until you're back to normal.
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What enzymes can you use in industry?
Protease can be used to pre-digest baby food. Carbohydrases can turn starch syrup to sugar syrup. Isomerase can turn glucose syrup into fructose syrup, which is sweeter (slimming foods)
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Advantages of using enzymes in industry?
Specific, only catalyse one reaction. Lower temperature/pressures mean lower cost. Continual use. Biodegradable thus causing less environmental pollution.
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Disadvantages of using enzymes in industry?
People can develop allergies. Can be denatured by small temp increase. Susceptible to poisons/pH changes. Expensive to produce. Contamination of the enzyme with other substances can affect the reaction.
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What is a gene?
A section of DNA containing the instructions to make a specific protein. They tell cells in what order to put the amino acids together.
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Does everyone have unique DNA?
Yes - except identical twins and clones
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What is the definition of mitosis? What is it used for?
When a cell reproduces itself by splitting to form two identical offspring. Its used to make new cells for growth and repair and in asexual reproduction.
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Describe mitosis
The DNA is copied and forms X-shaped chromosomes. They line up and cell fibres pull them apart. Membranes form around the sets, these become the nuclei. Then the cytoplasm divides. You get two identical cells, thus no variation.
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What is the definition of meiosis? What is it used for?
the production of cells which have 1/2 the normal number of chromosomes. Its used for sexual reproduction.
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Describe meiosis
DNA duplicates. The chromosome pairs line up and they're pulled apart so each new cell only has one copy. Then they divide again and the arms of the chromosomes are pulled apart. You get 4 gametes with a single set of chromosomes.
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What are stem cells? Where can you find them?
They are undifferentiated. Found in early human embryos, in adult bone marrow.
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Why are some people in favour of using embryos to create stem cells for research?
'Curing patients who are suffering is more important than the rights of embryos. The embryos used in shell cell research are usually unwanted. Any research will have strict guild lines.'
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Why are some people against of using embryos to create stem cells for research?
'Embryos shouldn't be used for experiments as they're potential human life. Scientists should focus on finding/developing other sources of stem cells.
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What can stem cells cure?
Blood diseases like sickle cell anemia and replace faulty cells
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How many pairs of chromosomes are there?
There are 22 pairs.
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What did Gregor Mendel do/discover?
Noted the characteristics of offspring by crossing tall and dwarf pea plants. His results showed that the unit for the tall plants were dominant
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What 3 conclusions came from Gregor Mendel's experiment?
Characteristics in plants are determined by hereditary units. Hereditary units are passed on, one from each parent. The units can be dominant/recessive.
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What are alleles, phenotypes and genotypes?
Alleles are different versions of the same gene, e.g. T/t. Genotypes are the alleles you have and phenotypes are the actual characteristic.
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What is meant by the terms heterozygous and homozygous?
Heterozygous is different alleles for a particular gene e.g. Tt. Homozygous is the same alleles for a particular gene e.g. tt
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What is cystic fibrosis? Is the allele that causes it recessive or dominant?
A genetic disorder of the cell membranes, resulting in the production of mucus in air passages and the pancreas. Its recessive. 1 allele=carrier. 2 alleles= sufferer.
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What is embryo screening?
During IVF, before embryos are implanted, you can remove a cell from each of them to analyse its genes. Disorders can be detected/'good' alleles used.
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Reasons against embryo screening?
Picking 'desirable' embryos. Rejected ones destroyed/potential life. It implies people with genetic orders are 'undesirable' which could increase prejudice. Expensive.
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Reasons for embryo screening?
Stop suffering. Laws to make limits. During IVF most embryos are destroyed anyway, screening just allows one to be healthy. Treating disorders costs the government and tax payers lots of money.
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What are fossils?
The remains of organisms from over 10,000 years ago.
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Other cards in this set

Card 2


Define a catalyst


A substance which increases the speed of a reaction, without being changed or used up in the reaction.

Card 3


What happens when an enzyme becomes denatured?


Preview of the front of card 3

Card 4


What would happen if you increase the substrate concentration in a reaction?


Preview of the front of card 4

Card 5


What do enzymes do in the digestive system?


Preview of the front of card 5
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