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OCR Biology A Paper 3
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OCR Biology A Paper 3
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OCR Biology A Paper 3Why are papers checked by scientists? - correct answer-peer review to check conclusions
drawn from data are valid
How do scientists share their data with the scientific community? - correct answer-Scientific
conferences, journals and blogs
What is critical evaluation of data by scientific community? - correct answer-Checking
methods, collecting more data and testing if the date can be replicated
Why is new data evaluated by other scientists? - correct answer-to check the experiments or
studies were designed properly and that the conclusions are fair
Description of nucleus - correct answer-Large organelle surrounded by a nuclear envelope
which contains pores. the nucleus contains chromatin (which is made from DNA and proteins
and a structure called the nucleolus.
What is the function of nucleus ? - correct answer-Controls the cells activities by controlling
the transcription of DNA. DNA contains instructions to make proteins. Pores allow
substances to move between the nucleus and cytoplasm. The nucleolus makes ribosomes
Description of lysosome - correct answer-A round organelle surrounded by a membrane with
no clear internal structure
What is the function of the lysozyme? - correct answer-Contains digestive enzymes which
are used to digest invading cells or break down worn components of the cell
Describe a ribosome - correct answer-A very small organelle that either floats free in the
cytoplasm or is attached to the rough endoplasmic reticulum. It is made up of proteins and
RNA. No membrane
What is the function of a ribosome? - correct answer-Function of ribosome ?Site where
proteins are synthesised
Describe the RER - correct answer-A system of membrane bound flattened sacs. the surface
is covered with ribosomes
What is the function of the RER? - correct answer-Folds and processes proteins that have
been made at the ribosomes
Describe the SER - correct answer-Description of smooth endoplasmic reticulum ?a system
of membrane bound flattened sacs but with no ribosomes
What is the function of the SER? - correct answer-Function of smooth endoplasmic reticulum
?synthesises and processes lipids
,Describe the Golgi apparatus - correct answer-A group of fluid filled membrane bound
flattened sacs. formed by the fusion of vesicles from the ER
What is the function of the Golgi apparatus? - correct answer-It processes and packages
new lipids and proteins. it also makes lysosomes
Describe the mitochondria - correct answer-Description of mitochondria ?Double membrane-
inner one is folded to form a structure called cristae. inside is the matrix which contains
enzymes involved in respiration
What is the function of the mitochondria? - correct answer-Function of mitochondria ?site of
aerobic respiration, where ATP is produced. found in large numbers in cells that are very
active and require a lot of energy.
Describe the centriole - correct answer-small hollow cylinders made of microtubules. found in
animal cells but only some plant cells
What is the function of the centriole? - correct answer-Involved with the separation of
chromosomes during cell division
What type of proteins do ribosomes make? - correct answer-Ribosomes on the rER make
proteins that are excreted or attached to the cell membrane. Free ribosomes in the
cytoplasm make proteins that stay in the cytoplasm.
What happens once the new proteins are made ? - correct answer-They enter into the rER
and are folded and processed. Then they are transported to the Golgi apparatus in vesicles.
The vesicles fuse to form the flattened sacs of the Golgi and the Golgi further processes the
proteins. The proteins enter more vesicles and are transported around the cell
What is found in the cytoplasm in prokaryotic cells? - correct answer-No membrane bound
organelles and has smaller ribosomes than in eukaryotic cell
What is the flagellum? - correct answer-long hair like structure that rotates to make the
prokaryotic cell move. not all prokaryotes have a flagellum and some have more than one
What is circular DNA? - correct answer-Long coiled up strand of DNA that is not attached to
any histone proteins
What is a plasmid? - correct answer-Small loops of DNA that aren't part of the main circular
DNA molecule. contain genes for things like antibiotic resistance
What is a mesosome? - correct answer-inward folds in the plasma membrane (thought to be
artifacts of cell staining and preparation)
What is a capsule? - correct answer-Made up of secreted slime. helps protect bacteria from
attack by cells of the immune system and prevents dehydration
,What is the Pilli? - correct answer-Short hair like structure. helps prokaryotes stick to other
cells and can be used to transfer genetic material between cells
What is the cell wall in prokaryotes made of? - correct answer-Support the cell and prevents
it from changing shape. made of murein glycoprotein or peptidoglycan
What is the function of the plasma membrane? - correct answer-Mainly made of lipids and
proteins. controls the movement of substances into and out of the cell
Description and function of the cell wall? - correct answer-rigid structure, mainly made of
cellulose, that surrounds and supports plant cells.
Description and function of the middle lamella - correct answer-outermost layer of the cell.
acts as an adhesive, sticking adjacent plant cells together. it gives the plant stability
Description and function of the plasmodesmata - correct answer-channels in the cell walls
that link adjacent cells together, allows transport of substances and communication between
cells
Description and function of the pits - correct answer-regions in the cell wall where the wall is
very thin. arranged in pairs so a pit in one cell is lined up with the pit in the adjacent cell.
allows transport of substances between cells
Description and function of the chloroplast - correct answer-small flattened structure. has a
double membrane and membranes inside called thylakoid membranes. thylakoid
membranes are stacked up in some parts to form grana. grana are linked together by
lamellae (thin pieces of thylakoid membrane). Site of photosynthesis
Description and function of the amyloplast - correct answer-small organelle enclosed by a
membrane. stores starch granules and converts the starch back to glucose for release when
the plant requires it
Description and function of the vacuole and tonoplast - correct answer-vacuole is a
compartment surrounded by a membrane called a tonoplast. vacuole contains cell sap which
is made up of water, enzymes, minerals and waste products. vacuoles keep cells turgid -
stops plants from wilting. also involved in the breakdown and isolation of unwanted
chemicals in the cell. tonoplast controls what enters and leaves vacuole
Why is water a polar molecule? - correct answer-Oxygen is more electronegative than
Hydrogen so there is a slight difference in charge between the atoms.
Why does water remain a liquid over a wide range of temperatures? - correct
answer-Hydrogen bonding holds water molecules together and collectively they make water
very stable
Why is water cohesive? - correct answer-the delta positive H is attracted to the delta
negative O. This helps water to flow so it is good at transporting substances
, Why is water a good solvent? - correct answer-Polar molecules and ionic substances
dissolve in water because water is dipolar. The forces of attraction between the delta positive
H and the delta negative O are stronger than the ionic bonds so the ions become hydrated
and completely surrounded by water molecules
Describe the structure of alpha glucose, with diagram - correct answer-six carbon
atoms/CHO elements only/OH below on C1
Describe the structure of beta glucose, with diagram - correct answer-six carbon atoms/CHO
elements only/OH above on C1
Describe the properties of glucose - correct answer-Monomer, soluble so easily transported.
Can affect osmotic potential
Describe (draw) how a monosaccharide is formed - correct answer-Condensation reaction
between two glucose monomers, 1-4 glycosidic bond
What type of reaction breaks a 1-4 glycosidic bond? - correct answer-Hydrolysis reaction
Two alpha glucose molecules are joined together to form.... - correct answer-Maltose
Alpha glucose + fructose = - correct answer-sucrose
Beta glucose + galactose = - correct answer-Lactose
Describe the structure of starch - correct answer-Insoluble carbohydrate, storage molecule in
plants, polysaccharide of alpha glucose, amylose (1-4 glycosidic, straight then spiraled),
amylopectin (1-4 and 1-6 glycosidic bonds, branched)
Describe the structure of glycogen - correct answer-Insoluble carbohydrate, storage
molecule in animals, polysaccharide of alpha glucose, 1-4 and 1-6 glycosidic bonds,
branched to enable easy hydrolysis
Describe the structure of a triglyceride (lipid) - correct answer-One glycerol joined to three
fatty acids by ester bonds (x3) in a condensation reaction. Fatty acid chains can be saturated
(single C-C bonds) or unsaturated (C=C bonds). Tail is hydrophobic, head hydrophilic .
Insoluble in water.
What is the difference between an mono and polyunsaturated fat? - correct answer-Mono =
one double bond, poly = many
Draw the formation of a triglyceride - correct answer-One glycerol joined to three fatty acids
by ester bonds (x3) in a condensation reaction. Fatty acid chains can be saturated (single
C-C bonds) or unsaturated (C=C bonds). Tail is hydrophobic, head hydrophilic . Insoluble in
water.
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