OCR GCSE Biology Exam Questions And
Answers Verified 100% Correct
What happens in protein synthesis? - ANSWER In the nucleus, the two DNA strands
unzip around the gene. The DNA is used as a template to make mRNA. Base pairing
ensures it is complementary. This is transcription. The mRNA molecule moves of of the
nucleus into the cytoplasm. Amino acids that match the triplet codes on mRNA join
together. This makes the protein coded for by the gene. This is called translation.
What is transcription? - ANSWER Transcription is the process by which the information
in a strand of DNA is copied into a new molecule of messenger RNA (mRNA).
What is translation? - ANSWER Translation is a step in protein biosynthesis wherein
the genetic code carried by mRNA is decoded to produce the specific sequence of
amino acids in a polypeptide chain.
Where are proteins synthesised? - ANSWER Proteins are synthesised in the
cytoplasm.
What are proteins made? - ANSWER Proteins are made from chains of molecules
called amino acid. Each protein has its own specific number and order of amino acids.
What is a polymer? - ANSWER A polymer is a large complex molecule composed of
long chains of monomers joined together.
What is a monomer? - ANSWER Monomers are small, basic molecular units.
What do nucleotides contain? - ANSWER Sugar and phosphate. The base of a each
nucleotide is the only part of the molecule that varies. The base is attached to the sugar.
What are the complementary base pairs? - ANSWER A(denine) *pairs with* T(hymine)
C(ytosine) *pairs with* G(uanine)
What shape is DNA? - ANSWER A double helix.
What are the two DNA strand made up of? - ANSWER The two DNA strands are made
up of nucleotides joined together in a long chain called polymers.
What do animal cells contain? - ANSWER Nucleus, Cytoplasm, Mitochondria, Cell
Membrane
,What is the function of a nucleus? - ANSWER It contains DNA and controls the cell's
activity.
What is the function of cytoplasm? - ANSWER Cytoplasm is a gel like substance where
chemical reactions occur.
What is the function of the mitochondria? - ANSWER It is the site of cellular respiration
and it contains enzymes which are needed for chemical reactions.
What is the function of the cell membrane? - ANSWER It holds the cell together and
controls what goes in and out of the cell by providing a selective barrier. They contain
receptor molecules that are used for cell communication.
What is a prokaryote? - ANSWER Prokaryotes are smaller and simpler cells.
What is a eukaryote? - ANSWER Eukaryotes are complex cells.
What is the equation for magnification? - ANSWER Magnification=image size/real size.
What are chromosomes? - ANSWER Chromosomes are long molecules of coiled up
DNA. The DNA is divided up into short sections called genes.
What do bacterial cells contain? - ANSWER Chromosomal DNA, Plasmids and a Cell
Membrane.
What is the function of chromosomal DNA? - ANSWER It is one long circular
chromosome which controls the cells activities and replication. It floats in the cytoplasm.
What is the function of a plasmid? - ANSWER A plasmid is a small loop of extra DNA
that is not a part of the chromosome. Plasmids contain genes for things like drug
resistance and it can be passed on between bacteria.
What do plant cells have that animal cells do not? - ANSWER Cell wall, chloroplasts.
What is the function of the cell wall? - ANSWER It provides support and it is made up of
cellulose.
What are the functions of chloroplasts? - ANSWER They carry out photosynthesis (it's
where it occurs) and they contain chlorophyll.
What is the cell cycle? - ANSWER It is when cells in the body divide to produce more
cells, so your body can grow and replace damaged cells and cells grow and divide over
and over again.
,What are the three separate growth stages called? - ANSWER G, S and G2
What is 'gap phase one'? - ANSWER At this phase, the cell grows and new cell
structures and proteins are made.
What is the 'S' phase? - ANSWER At this phase, cells replicate its DNA, so that when it
splits during mitosis and the two new cells will contain identical DNA.
What is 'gap phase two'? - ANSWER At this phase, cells keep growing and proteins
needed for cell division are made.
Where does the cell cycle start and end? - ANSWER With mitosis.
Define mitosis. - ANSWER Mitosis is when a cell reproduces itself by splitting to form
two identical offspring.
What is the first stage of mitosis? - ANSWER The cell has two copies of its DNA all
spread out in long strings.
What is the second stage of mitosis? - ANSWER The DNA forms X-shaped
chromosomes. Each 'arm' of a chromosome is an exact copy of the other. This
happens before the cell divides.
What is the third stage of mitosis? - ANSWER The chromosomes then line up at the
center of the cell and cell fibers pull them apart. The two arms of each chromosome go
to opposite ends of the cell.
What is the fourth stage of mitosis? - ANSWER Membranes from around each of the
sets of chromosomes. these become nuclei of the two new cells.
What is the fifth and final stage of mitosis? - ANSWER The cytoplasm divides; two new
cells containing exactly the same DNA as they're genetically identical to each other and
to the parent cell.
What is differentiation? - ANSWER Differentiation is the process by which a cell
changes to become specialised for its job.
What is an example of differentiation in plants? - ANSWER Palisade leaf cells carry out
photosynthesis as they contain chloroplasts. Their tall shape means that they have a lot
of surface area exposed down the side for absorbing carbon dioxide from the air in the
leaf, and their thin shape means that you can fit loads of them in at the top of a leaf, so
they're nearer the light.
, What is an example of differentiation in animals and humans? - ANSWER A sperm's
function is to get the male DNA to the female DNA during reproduction. Sperm have
long tails and streamlined heads to help them swim, they contain lots of mitochondria
to provide them with energy and they have enzymes in their heads to digest through
the egg's cell membrane.
What do specialised cells in multicellular organisms do in order to carry out their
function? - ANSWER In multicellular organisms, specialised cells are grouped
together to form tissues- groups of cells working together to perform a particular
function. Different tissues work together to form organs. Different organs make up an
organ system.
What is an example of an undifferentiated cell? - ANSWER Stem cells are
undifferentiated but depending on what instructions they're given, they can divide by
mitosis to become new cells, which then differentiate.
Why are embryonic stem cells so important for growth and repair? - ANSWER They
have the potential to become any kind of cell.
Where can you find stem cells in the body? - ANSWER In adults, stem cells can be
found in bone marrow. You can also find them in the umbilical cord.
What is the main disadvantage of stem cells? - ANSWER They cannot turn into any
type of cell.
What are the only cells in plants that divide by mitosis? - ANSWER Meristems- they are
found in plant tissues.
Where is meristem tissue found in the plant? - ANSWER Anywhere in the plant thats
growing- e.g the roots and shoots.
What type of cells do meristems produce? - ANSWER They produce unspecialised
cells that are able to divide into any cell type in the plant and they act like embryonic
stem cells.
What can the unspecialised cells in the plant become? - ANSWER They can become
specialised and form tissues like xylem and phloem.
What is diffusion? - ANSWER Diffusion is the net (overall) movement of particles from
an area of higher concentration to an area of lower concentration.
In what states can diffusion occur? - ANSWER Liquids and gases as the particles are
free to move around.
Answers Verified 100% Correct
What happens in protein synthesis? - ANSWER In the nucleus, the two DNA strands
unzip around the gene. The DNA is used as a template to make mRNA. Base pairing
ensures it is complementary. This is transcription. The mRNA molecule moves of of the
nucleus into the cytoplasm. Amino acids that match the triplet codes on mRNA join
together. This makes the protein coded for by the gene. This is called translation.
What is transcription? - ANSWER Transcription is the process by which the information
in a strand of DNA is copied into a new molecule of messenger RNA (mRNA).
What is translation? - ANSWER Translation is a step in protein biosynthesis wherein
the genetic code carried by mRNA is decoded to produce the specific sequence of
amino acids in a polypeptide chain.
Where are proteins synthesised? - ANSWER Proteins are synthesised in the
cytoplasm.
What are proteins made? - ANSWER Proteins are made from chains of molecules
called amino acid. Each protein has its own specific number and order of amino acids.
What is a polymer? - ANSWER A polymer is a large complex molecule composed of
long chains of monomers joined together.
What is a monomer? - ANSWER Monomers are small, basic molecular units.
What do nucleotides contain? - ANSWER Sugar and phosphate. The base of a each
nucleotide is the only part of the molecule that varies. The base is attached to the sugar.
What are the complementary base pairs? - ANSWER A(denine) *pairs with* T(hymine)
C(ytosine) *pairs with* G(uanine)
What shape is DNA? - ANSWER A double helix.
What are the two DNA strand made up of? - ANSWER The two DNA strands are made
up of nucleotides joined together in a long chain called polymers.
What do animal cells contain? - ANSWER Nucleus, Cytoplasm, Mitochondria, Cell
Membrane
,What is the function of a nucleus? - ANSWER It contains DNA and controls the cell's
activity.
What is the function of cytoplasm? - ANSWER Cytoplasm is a gel like substance where
chemical reactions occur.
What is the function of the mitochondria? - ANSWER It is the site of cellular respiration
and it contains enzymes which are needed for chemical reactions.
What is the function of the cell membrane? - ANSWER It holds the cell together and
controls what goes in and out of the cell by providing a selective barrier. They contain
receptor molecules that are used for cell communication.
What is a prokaryote? - ANSWER Prokaryotes are smaller and simpler cells.
What is a eukaryote? - ANSWER Eukaryotes are complex cells.
What is the equation for magnification? - ANSWER Magnification=image size/real size.
What are chromosomes? - ANSWER Chromosomes are long molecules of coiled up
DNA. The DNA is divided up into short sections called genes.
What do bacterial cells contain? - ANSWER Chromosomal DNA, Plasmids and a Cell
Membrane.
What is the function of chromosomal DNA? - ANSWER It is one long circular
chromosome which controls the cells activities and replication. It floats in the cytoplasm.
What is the function of a plasmid? - ANSWER A plasmid is a small loop of extra DNA
that is not a part of the chromosome. Plasmids contain genes for things like drug
resistance and it can be passed on between bacteria.
What do plant cells have that animal cells do not? - ANSWER Cell wall, chloroplasts.
What is the function of the cell wall? - ANSWER It provides support and it is made up of
cellulose.
What are the functions of chloroplasts? - ANSWER They carry out photosynthesis (it's
where it occurs) and they contain chlorophyll.
What is the cell cycle? - ANSWER It is when cells in the body divide to produce more
cells, so your body can grow and replace damaged cells and cells grow and divide over
and over again.
,What are the three separate growth stages called? - ANSWER G, S and G2
What is 'gap phase one'? - ANSWER At this phase, the cell grows and new cell
structures and proteins are made.
What is the 'S' phase? - ANSWER At this phase, cells replicate its DNA, so that when it
splits during mitosis and the two new cells will contain identical DNA.
What is 'gap phase two'? - ANSWER At this phase, cells keep growing and proteins
needed for cell division are made.
Where does the cell cycle start and end? - ANSWER With mitosis.
Define mitosis. - ANSWER Mitosis is when a cell reproduces itself by splitting to form
two identical offspring.
What is the first stage of mitosis? - ANSWER The cell has two copies of its DNA all
spread out in long strings.
What is the second stage of mitosis? - ANSWER The DNA forms X-shaped
chromosomes. Each 'arm' of a chromosome is an exact copy of the other. This
happens before the cell divides.
What is the third stage of mitosis? - ANSWER The chromosomes then line up at the
center of the cell and cell fibers pull them apart. The two arms of each chromosome go
to opposite ends of the cell.
What is the fourth stage of mitosis? - ANSWER Membranes from around each of the
sets of chromosomes. these become nuclei of the two new cells.
What is the fifth and final stage of mitosis? - ANSWER The cytoplasm divides; two new
cells containing exactly the same DNA as they're genetically identical to each other and
to the parent cell.
What is differentiation? - ANSWER Differentiation is the process by which a cell
changes to become specialised for its job.
What is an example of differentiation in plants? - ANSWER Palisade leaf cells carry out
photosynthesis as they contain chloroplasts. Their tall shape means that they have a lot
of surface area exposed down the side for absorbing carbon dioxide from the air in the
leaf, and their thin shape means that you can fit loads of them in at the top of a leaf, so
they're nearer the light.
, What is an example of differentiation in animals and humans? - ANSWER A sperm's
function is to get the male DNA to the female DNA during reproduction. Sperm have
long tails and streamlined heads to help them swim, they contain lots of mitochondria
to provide them with energy and they have enzymes in their heads to digest through
the egg's cell membrane.
What do specialised cells in multicellular organisms do in order to carry out their
function? - ANSWER In multicellular organisms, specialised cells are grouped
together to form tissues- groups of cells working together to perform a particular
function. Different tissues work together to form organs. Different organs make up an
organ system.
What is an example of an undifferentiated cell? - ANSWER Stem cells are
undifferentiated but depending on what instructions they're given, they can divide by
mitosis to become new cells, which then differentiate.
Why are embryonic stem cells so important for growth and repair? - ANSWER They
have the potential to become any kind of cell.
Where can you find stem cells in the body? - ANSWER In adults, stem cells can be
found in bone marrow. You can also find them in the umbilical cord.
What is the main disadvantage of stem cells? - ANSWER They cannot turn into any
type of cell.
What are the only cells in plants that divide by mitosis? - ANSWER Meristems- they are
found in plant tissues.
Where is meristem tissue found in the plant? - ANSWER Anywhere in the plant thats
growing- e.g the roots and shoots.
What type of cells do meristems produce? - ANSWER They produce unspecialised
cells that are able to divide into any cell type in the plant and they act like embryonic
stem cells.
What can the unspecialised cells in the plant become? - ANSWER They can become
specialised and form tissues like xylem and phloem.
What is diffusion? - ANSWER Diffusion is the net (overall) movement of particles from
an area of higher concentration to an area of lower concentration.
In what states can diffusion occur? - ANSWER Liquids and gases as the particles are
free to move around.
