Edexcel Biology B2 Topic 1

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Name the four parts of a cell that both plants and animals have.
Cell membrane, nucleus, mitochondria and cytoplasm.
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Name the three things plant cells have but animal cells do not.
Cellulose cell wall, chloroplasts and a vacuole.
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What four features does a bacterial cell have?
Chromosomal DNA, cell wall, plasmids and flagellum.
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How do you calculate magnification?
Magnification= length of image/length of specimen.
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What structure does a DNA molecule have?
A double helix (two strands coiled together).
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DNA is held together by four different bases. What are they?
Adenine (A), cytosine (C), guanine (G) and thymine (T).
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The bases are always paired. Which bases pair up?
Adenine and thymine, cytosine and guanine. A-T, C-G.
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How are the base pairs joined together?
Weak hydrogen bonds.
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Who discovered that DNA has a helical structure by using x-rays?
Franklin and Wilkins.
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Who used this information to create a model of DNA's structure?
Watson and Crick.
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How many bases code for a particular amino acid?
Three- it's called a triplet.
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What organelles are proteins made in?
Ribosomes.
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Where is DNA found?
In the nucleus.
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What acts as a messenger between the nucleus and the ribosome?
mRNA
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What are the properties of mRNA?
Similar to DNA, but shorter and only a single strand.
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What is transcription?
The DNA unzips and one strand is used as a template to make the mRNA.
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What is translation?
The ribosome sticks amino acids together to form a polypeptide.
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Which base replaces thymine in mRNA?
Uracil (U).
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What is a mutation?
A change to an organism's DNA base sequence.
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Give an example of a harmful mutation.
A genetic disorder, for example cystic fibrosis.
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Give an example of a beneficial mutation.
New beneficial characteristics may be produced; such as bacteria becoming antibiotic resistant.
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How can a mutation be neutral?
They are neither beneficial or harmful; they may not affect a protein's function.
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What are enzymes?
Biological catalysts.
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What is a catalyst?
A substance that speeds up a reaction without being changed or used up.
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How are enzymes used in DNA replication?
They help copy a cells DNA before it divides.
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How are enzymes used in protein synthesis?
They hold amino acids in place and form bonds between them.
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How are enzymes used in digestion?
Various enzymes are secreted in the gut to digest different food molecules.
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What is a substrate?
The molecule that is changed in a reaction.
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What is an active site?
The part of an enzyme which the substrate joins on to in order to catalyse a reaction.
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Enzymes have a high specificity for their substrate. What does this mean?
They only work with one substrate.
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What is the 'lock and key' mechanism?
A substrate has to be the right size and shape to fit in an active site.
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What is the optimum temperature for enzymes in the human body?
37°C.
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What happens if an enzyme gets too hot?
It denatures (loses its shape).
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What is the optimum pH for most enzymes?
pH 7, which is neutral.
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Give an example of an enzyme which does not have an optimum pH of 7.
Pepsin's optimum pH is 2, making it well suited to the acidity of the stomach.
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A higher substrate concentration will make the reaction faster. True or false?
True, up until a certain point. All the active sites will be filled, so adding more will not make a difference.
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What did the Human Genome Project aim to find?
Every single human gene.
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Where did the scientists that worked on the Human Genome Project come from?
All over the world.
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Give an example of a good impact of the Human Genome Project.
Prediction and prevention of disease, better medicines, accurate diagnoses and improved forensic science.
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Other cards in this set

Card 2

Front

Name the three things plant cells have but animal cells do not.

Back

Cellulose cell wall, chloroplasts and a vacuole.

Card 3

Front

What four features does a bacterial cell have?

Back

Preview of the front of card 3

Card 4

Front

How do you calculate magnification?

Back

Preview of the front of card 4

Card 5

Front

What structure does a DNA molecule have?

Back

Preview of the front of card 5
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