Biology GCSE
What are the parts of an animal (and plant) cell? - Answer Nucleus
Cytoplasm
Cell membrane
Mitochondria
What are parts of a plant cell? - Answer Rigid cell wall
Large vacuole
Chloroplasts
(nucleus, cytoplasm, cell membrane and mitochondria)
What does the nucleus do? - Answer Contains DNA that controls what the cell does
What does the cytoplasm do? - Answer Its a gel-like substance where most of the
chemical reactions happpen
What does the cell membrane do? - Answer Holds the cell together and controls what
goes in and out
What does the mitochondria do? - Answer This is where most of the reactions for
respiration take place. Respiration releases energy that the cell needs to work.
What does the rigid cell wall do? - Answer It is made up of cellulose and it gives support
for the cell
What does the large vacuole do? - Answer Contains cell sap, a weak solution of sugar
and salts
What do chloroplasts do? - Answer This is where photosynthesis occurs. They contain a
green substance called chlorophyll.
What are the features of a bacteria cell? - Answer Chromosomal DNA
Plasmids
Flagellum
Cell wall
What is chromosomal DNA? - Answer Chromosomal DNA controls the cells activities
and replication. It floats free in the cytoplasm.
What are plasmids? - Answer Plasmids are small loops of extra DNA that aren't part of
the chromosome. Plasmids contain genes for things like drug resistance and can be
passed between bacteria.
What is the flagellum? - Answer The flagellum is a long, hair-like structure that rotates to
make the bacterium move.
What does the cell wall do? - Answer Support the cell
,Biology GCSE
What is magnification? - Answer How much bigger the image is that the specimen
How do you work out magnification? - Answer length of image / length of specimen
What is the difference between light microscopes and electron microscopes? - Answer
Light microscopes let us see things like the nuclei, chloroplasts and mitochondria.
Electron microscopes let us see much smaller things in more detail like the internal
structure of mitochondria and chloroplasts and even tinier things like plasmids.
What is DNA? - Answer DNA is the complex chemical that carries genetic information.
DNA is found in chromosomes which are found in the nucleus of most cells.
What is the structure of DNA? (6marker) - Answer -A DNA molecule has two strands
coiled together in the shape of a double helix.
-The two strands are hold together by chemicals called bases. The four bases are
adenine, thymine, guanine and cytosine.
-The bases are paired, and they always pair up in the same way; A-T and C-G. This is
called base pairing.
-The base pairs are joined together by weak hydrogen bonds.
What is a gene? - Answer A gene is a short piece of DNA that codes for a specific
protein. You have genes for hair structure, eye colour enzymes and every other protein
in your body.
Who discovered the structure of DNA? - Answer -Rosalind Franklin and Maurice Wilkins
worked out DNA had a helical structure by directing beams of X-rays onto crystallised
DNA and looking at the patterns of x-rays formed as they bounced off.
-James Watson and Francis Crick used these ideas along with the idea the amount of
adenine+guanine matched the amount of thymine+cytosine to make a model of the
DNA molecule where all the pieces fitted together.
What would be a practical to extract DNA?(6 marker) - Answer -Mash or chop fruit or
vegetable (e.g kiwi) and mix with salty water and detergent to break open the cells and
help release the DNA from the nuclei.
-Add protease enzyme to the filtered mixture to break up proteins in cell membranes
and so release more DNA.
-Add ice cold ethanol carefully down inside the tube into the mixture. The ethanol makes
the DNA separate from the liquid so it is easy to lift out.
How does a cell make proteins? - Answer By stringing amino acids together in a
particular order. There's only 20 different amino acids that are used to make up
thousands of different proteins. The order of bases in a gene tells cells in what order to
put the amino acids together. Each set of three bases (triplet) codes for a particular
amino acid.
, Biology GCSE
What can DNA determine? - Answer Which genes are switched on or off and so which
proteins the cell produces e.g keratin. That in turn determines what type of cell it is e.g.
red blood cell, skin cell.
What are proteins made by? - Answer Proteins are made in the cell by oraganelles
called ribosomes.
Why does the cell need mRNA? - Answer Because DNA is found in the nucleus and
can't move out of it because its too big. The cell needs to get the information from the
DNA to the ribosome in the cell cytoplasm. This is done by using a molecule called
mRNA, which is very similar to DNA, but it's shorter and only a single strand. Also,
instead of thymine, mRNA has the base uracil (u), which pairs with adenine. mRNA is
like a messanger between the DNA in the nucleus and the ribosome. It happens during
transcription and translation.
What happens during transcription? - Answer -Transcription takes place in the nucleus.
-The weak hydrogen bonds break and a section of DNA is unwound and the two strands
separate.
-One strand is used as a template.
-Complementary bases to this strand link to it.
-mRNA is formed.
-mRNA stands for messenger RNA
-mRNA moves out of the nucleus into the cells cytoplasm
What happens during translation? - Answer -Translation takes place in the cytoplasm
when the mRNA attaches to a ribosome.
-The ribosome moves along the mRNA in one direction reading a triplet of bases
(codon) at a time.
-tRNA molecules bring amino acids to thee ribosome. The amino acids attached to each
tRNA molecule depends on the order of bases in the tRNA.
-Complementary bases of tRNA pair with the bases of the mRNA strand.
-Amino acids that are close together are joined to make an amino acid chain (a
polypeptide)
-Every protein is formed from a specific number of amino acids in a particular order. The
order of the bases in the DNA defines the order in which the amino acids are joined
together. So one section of DNA codes for one particular protein.
What do mutations do? - Answer A mutation is a change in an organisms DNA base
sequence. This may change the amino acid that is added to the chain during translation
on the ribosome.
What could a harmful mutation change do? - Answer A harmful mutation could cause a
genetic disorder, for example, cystic fibrosis
What are the parts of an animal (and plant) cell? - Answer Nucleus
Cytoplasm
Cell membrane
Mitochondria
What are parts of a plant cell? - Answer Rigid cell wall
Large vacuole
Chloroplasts
(nucleus, cytoplasm, cell membrane and mitochondria)
What does the nucleus do? - Answer Contains DNA that controls what the cell does
What does the cytoplasm do? - Answer Its a gel-like substance where most of the
chemical reactions happpen
What does the cell membrane do? - Answer Holds the cell together and controls what
goes in and out
What does the mitochondria do? - Answer This is where most of the reactions for
respiration take place. Respiration releases energy that the cell needs to work.
What does the rigid cell wall do? - Answer It is made up of cellulose and it gives support
for the cell
What does the large vacuole do? - Answer Contains cell sap, a weak solution of sugar
and salts
What do chloroplasts do? - Answer This is where photosynthesis occurs. They contain a
green substance called chlorophyll.
What are the features of a bacteria cell? - Answer Chromosomal DNA
Plasmids
Flagellum
Cell wall
What is chromosomal DNA? - Answer Chromosomal DNA controls the cells activities
and replication. It floats free in the cytoplasm.
What are plasmids? - Answer Plasmids are small loops of extra DNA that aren't part of
the chromosome. Plasmids contain genes for things like drug resistance and can be
passed between bacteria.
What is the flagellum? - Answer The flagellum is a long, hair-like structure that rotates to
make the bacterium move.
What does the cell wall do? - Answer Support the cell
,Biology GCSE
What is magnification? - Answer How much bigger the image is that the specimen
How do you work out magnification? - Answer length of image / length of specimen
What is the difference between light microscopes and electron microscopes? - Answer
Light microscopes let us see things like the nuclei, chloroplasts and mitochondria.
Electron microscopes let us see much smaller things in more detail like the internal
structure of mitochondria and chloroplasts and even tinier things like plasmids.
What is DNA? - Answer DNA is the complex chemical that carries genetic information.
DNA is found in chromosomes which are found in the nucleus of most cells.
What is the structure of DNA? (6marker) - Answer -A DNA molecule has two strands
coiled together in the shape of a double helix.
-The two strands are hold together by chemicals called bases. The four bases are
adenine, thymine, guanine and cytosine.
-The bases are paired, and they always pair up in the same way; A-T and C-G. This is
called base pairing.
-The base pairs are joined together by weak hydrogen bonds.
What is a gene? - Answer A gene is a short piece of DNA that codes for a specific
protein. You have genes for hair structure, eye colour enzymes and every other protein
in your body.
Who discovered the structure of DNA? - Answer -Rosalind Franklin and Maurice Wilkins
worked out DNA had a helical structure by directing beams of X-rays onto crystallised
DNA and looking at the patterns of x-rays formed as they bounced off.
-James Watson and Francis Crick used these ideas along with the idea the amount of
adenine+guanine matched the amount of thymine+cytosine to make a model of the
DNA molecule where all the pieces fitted together.
What would be a practical to extract DNA?(6 marker) - Answer -Mash or chop fruit or
vegetable (e.g kiwi) and mix with salty water and detergent to break open the cells and
help release the DNA from the nuclei.
-Add protease enzyme to the filtered mixture to break up proteins in cell membranes
and so release more DNA.
-Add ice cold ethanol carefully down inside the tube into the mixture. The ethanol makes
the DNA separate from the liquid so it is easy to lift out.
How does a cell make proteins? - Answer By stringing amino acids together in a
particular order. There's only 20 different amino acids that are used to make up
thousands of different proteins. The order of bases in a gene tells cells in what order to
put the amino acids together. Each set of three bases (triplet) codes for a particular
amino acid.
, Biology GCSE
What can DNA determine? - Answer Which genes are switched on or off and so which
proteins the cell produces e.g keratin. That in turn determines what type of cell it is e.g.
red blood cell, skin cell.
What are proteins made by? - Answer Proteins are made in the cell by oraganelles
called ribosomes.
Why does the cell need mRNA? - Answer Because DNA is found in the nucleus and
can't move out of it because its too big. The cell needs to get the information from the
DNA to the ribosome in the cell cytoplasm. This is done by using a molecule called
mRNA, which is very similar to DNA, but it's shorter and only a single strand. Also,
instead of thymine, mRNA has the base uracil (u), which pairs with adenine. mRNA is
like a messanger between the DNA in the nucleus and the ribosome. It happens during
transcription and translation.
What happens during transcription? - Answer -Transcription takes place in the nucleus.
-The weak hydrogen bonds break and a section of DNA is unwound and the two strands
separate.
-One strand is used as a template.
-Complementary bases to this strand link to it.
-mRNA is formed.
-mRNA stands for messenger RNA
-mRNA moves out of the nucleus into the cells cytoplasm
What happens during translation? - Answer -Translation takes place in the cytoplasm
when the mRNA attaches to a ribosome.
-The ribosome moves along the mRNA in one direction reading a triplet of bases
(codon) at a time.
-tRNA molecules bring amino acids to thee ribosome. The amino acids attached to each
tRNA molecule depends on the order of bases in the tRNA.
-Complementary bases of tRNA pair with the bases of the mRNA strand.
-Amino acids that are close together are joined to make an amino acid chain (a
polypeptide)
-Every protein is formed from a specific number of amino acids in a particular order. The
order of the bases in the DNA defines the order in which the amino acids are joined
together. So one section of DNA codes for one particular protein.
What do mutations do? - Answer A mutation is a change in an organisms DNA base
sequence. This may change the amino acid that is added to the chain during translation
on the ribosome.
What could a harmful mutation change do? - Answer A harmful mutation could cause a
genetic disorder, for example, cystic fibrosis
