Year 11 GCSE Exam Revision – Paper 1 (Biology)
Key Concepts:
Animal & Plant Cells
Animal cells and plant cells have different functions and structures. Animal cells are the building
blocks that make up all the living organisms and the structure of the animal cell has the nucleus,
ribosome, mitochondria, cell membrane, cytoplasm and vacuole, which is used to perform
different features in the living things. However, plant cells are different from animal cells
because they are the fundamental building blocks of plant life because they do the process for
survival like photosynthesis. Plant cells are responsible for performing the function
photosynthesis as a result we refer green plants as autotrophs (is an organism that can produce
its own food using light, water, carbon dioxide, or other chemicals) It is done due to the
presence of chlorophyll in the chloroplast. Cellus gives support to the cells. Both animal and
plant cells have mitochondria but only plants have chloroplast. This is because plants don’t get
sugar from eating food, so they need to make sugar from light by using the process
photosynthesis. In the chloroplast, once sugar is made it is breakdown by mitochondria to
release energy from cell because animals get sugar from the food, they eat so they don’t need
chloroplasts, but they need mitochondria. Plant cells contain large vacuoles used for storage
and to maintain cell shape. The plant cell's structure has nucleus, cell wall, cell membrane,
cytoplasm, vacuole and mainly the chloroplast, and these are used to perform different
features in plant cells. Both animal and plant cells are eukaryotic, so they contain membrane
bound organelle like nucleus and mitochondria.
Prokaryotic and Eukaryotic cell:
All living organisms fall into one of these 2 groups. They’re eukaryotic or prokaryotic cell
Cellular structure determines which group an organism belongs to. Prokaryotic cells are
unicellular organisms that lack membrane bound structure. Prokaryotic cells are small and
simple cells which measure 0.1 - 0.5 micrometers/ diameter. In prokaryotic cells, DNA bundles
together in a region called nucleoid. They split into 2 domains, one is bacteria, and the other
one is archaea. In prokariods, molecules of protein, DNA and metabolites are all found together
floating in cytoplasm. A eukaryotic cell contains membrane-bound organelles such as a nucleus,
mitochondria, and an endoplasmic reticulum. Organisms based on the eukaryotic cell include
protozoa, fungi, plants, and animals. These organisms are grouped into the biological domain of
eukaryote. Eukaryotic cells are larger and more complex than prokaryotic cells found in
domains archaea and bacteria.
Microscopy:
Magnification – Process of enlarging an object to make specific features visible to the human
eye.
,Resolution – It increases the amount of detail, and we can see, increasing our ability to
distinguish between 2 parts of an object.
Total magnification = eyes piece lens x objective lens
Magnification = Image size ÷ Actual size
Actual Image = Image size ÷ Total magnification
Image size = Actual Image x Total magnification
What is the difference between a light microscope and an electron microscope?
The main difference between them is that in an electron microscope, a beam of electrons is
used for magnifying the image of an object while visible light is used in the light microscope to
magnify images of tiny areas of materials or biological specimens.
Electron microscopies are better as they offer a better resolution than light microscopes and
can reveal the structure of smaller objects. This is because the wavelength of electrons is up to
100,000 shorter than visible light photons.
Diffusion, Osmosis & Active Transport:
Diffusion – The movement of particles from a high concentration to low concentration through
the concentration gradient.
Factors affecting diffusion:
• Thick walls (membrane thickness) affect diffusion because it is hard for gas exchange to
occur.
• Increase in surface area affects Diffusion because there will be more room for gas
exchange to occur.
• Temperature affects diffusion because if the temperature is warm the particles will
move faster due to the increase of kinetic energy causing collision.
Osmosis- The movement of particles from a high concentration to low concentration across a
partially permeable membrane.
3 factors that affect osmosis:
, • The water potential gradient (the higher the water potential gradient, the faster the rate
of osmosis).
• The thickness of the membrane (the thinner the membrane, the faster the rate of
osmosis).
• Surface area of the exchange surface (the larger the surface area, the faster the rate of
osmosis).
Active transport- The movement of particles from a low concentration to high concentration
against a concentration gradient. This therefore requires energy.
Enzymes:
Enzymes are proteins that act as biological catalyst meaning that it speeds up chemical reaction
and breaks down food in digestion. For example, amylase is breakdown into starch to produce
glucose, protease is breakdown into protein to produce amino acid and lipase is breakdown in
lipid to produce glycerol and fatty acid. Enzymes are measured by PH levels and have an
amazing high-rate reaction. Enzyme works on substrates forming products. Enzyme and
substrate collide to form enzyme – substrate complexes.
Substrate breaks down and products are released, and enzymes will start their reaction again.
This is called the lock and key model. Lock and key model explain why enzyme works with only
1 substrate.
Enzyme Substrate Product
Amylase Starch Glucose/Simple sugar
Protease Protein Amino acids
Lipase Lipids Glycerol/ Fatty acids
Enzymes are used for aiding digestion and metabolism. Some enzymes help to breakdown large
things to small things to easily absorb it. Other enzymes help bind molecules together to make
1 molecule.
A substance that helps a reaction go faster without being changed itself is called catalyst.
Key Concepts:
Animal & Plant Cells
Animal cells and plant cells have different functions and structures. Animal cells are the building
blocks that make up all the living organisms and the structure of the animal cell has the nucleus,
ribosome, mitochondria, cell membrane, cytoplasm and vacuole, which is used to perform
different features in the living things. However, plant cells are different from animal cells
because they are the fundamental building blocks of plant life because they do the process for
survival like photosynthesis. Plant cells are responsible for performing the function
photosynthesis as a result we refer green plants as autotrophs (is an organism that can produce
its own food using light, water, carbon dioxide, or other chemicals) It is done due to the
presence of chlorophyll in the chloroplast. Cellus gives support to the cells. Both animal and
plant cells have mitochondria but only plants have chloroplast. This is because plants don’t get
sugar from eating food, so they need to make sugar from light by using the process
photosynthesis. In the chloroplast, once sugar is made it is breakdown by mitochondria to
release energy from cell because animals get sugar from the food, they eat so they don’t need
chloroplasts, but they need mitochondria. Plant cells contain large vacuoles used for storage
and to maintain cell shape. The plant cell's structure has nucleus, cell wall, cell membrane,
cytoplasm, vacuole and mainly the chloroplast, and these are used to perform different
features in plant cells. Both animal and plant cells are eukaryotic, so they contain membrane
bound organelle like nucleus and mitochondria.
Prokaryotic and Eukaryotic cell:
All living organisms fall into one of these 2 groups. They’re eukaryotic or prokaryotic cell
Cellular structure determines which group an organism belongs to. Prokaryotic cells are
unicellular organisms that lack membrane bound structure. Prokaryotic cells are small and
simple cells which measure 0.1 - 0.5 micrometers/ diameter. In prokaryotic cells, DNA bundles
together in a region called nucleoid. They split into 2 domains, one is bacteria, and the other
one is archaea. In prokariods, molecules of protein, DNA and metabolites are all found together
floating in cytoplasm. A eukaryotic cell contains membrane-bound organelles such as a nucleus,
mitochondria, and an endoplasmic reticulum. Organisms based on the eukaryotic cell include
protozoa, fungi, plants, and animals. These organisms are grouped into the biological domain of
eukaryote. Eukaryotic cells are larger and more complex than prokaryotic cells found in
domains archaea and bacteria.
Microscopy:
Magnification – Process of enlarging an object to make specific features visible to the human
eye.
,Resolution – It increases the amount of detail, and we can see, increasing our ability to
distinguish between 2 parts of an object.
Total magnification = eyes piece lens x objective lens
Magnification = Image size ÷ Actual size
Actual Image = Image size ÷ Total magnification
Image size = Actual Image x Total magnification
What is the difference between a light microscope and an electron microscope?
The main difference between them is that in an electron microscope, a beam of electrons is
used for magnifying the image of an object while visible light is used in the light microscope to
magnify images of tiny areas of materials or biological specimens.
Electron microscopies are better as they offer a better resolution than light microscopes and
can reveal the structure of smaller objects. This is because the wavelength of electrons is up to
100,000 shorter than visible light photons.
Diffusion, Osmosis & Active Transport:
Diffusion – The movement of particles from a high concentration to low concentration through
the concentration gradient.
Factors affecting diffusion:
• Thick walls (membrane thickness) affect diffusion because it is hard for gas exchange to
occur.
• Increase in surface area affects Diffusion because there will be more room for gas
exchange to occur.
• Temperature affects diffusion because if the temperature is warm the particles will
move faster due to the increase of kinetic energy causing collision.
Osmosis- The movement of particles from a high concentration to low concentration across a
partially permeable membrane.
3 factors that affect osmosis:
, • The water potential gradient (the higher the water potential gradient, the faster the rate
of osmosis).
• The thickness of the membrane (the thinner the membrane, the faster the rate of
osmosis).
• Surface area of the exchange surface (the larger the surface area, the faster the rate of
osmosis).
Active transport- The movement of particles from a low concentration to high concentration
against a concentration gradient. This therefore requires energy.
Enzymes:
Enzymes are proteins that act as biological catalyst meaning that it speeds up chemical reaction
and breaks down food in digestion. For example, amylase is breakdown into starch to produce
glucose, protease is breakdown into protein to produce amino acid and lipase is breakdown in
lipid to produce glycerol and fatty acid. Enzymes are measured by PH levels and have an
amazing high-rate reaction. Enzyme works on substrates forming products. Enzyme and
substrate collide to form enzyme – substrate complexes.
Substrate breaks down and products are released, and enzymes will start their reaction again.
This is called the lock and key model. Lock and key model explain why enzyme works with only
1 substrate.
Enzyme Substrate Product
Amylase Starch Glucose/Simple sugar
Protease Protein Amino acids
Lipase Lipids Glycerol/ Fatty acids
Enzymes are used for aiding digestion and metabolism. Some enzymes help to breakdown large
things to small things to easily absorb it. Other enzymes help bind molecules together to make
1 molecule.
A substance that helps a reaction go faster without being changed itself is called catalyst.
