CIE Biology AS Level: 490 Well Defined
Terms with Certified Solutions 2023-2024
Eukaryote
Organisms who possess nuclei; includes plants, animals, fungi and unicellular
organisms known as protoctists; DNA is linear and bound to proteins to form chromatin.
Prokaryote
Organisms that lack nuclei; usually 1000 x - 10000 x smaller in volume than eukaryotes;
DNA is circular and free in the cytoplasm; known as simplest cells; contain 70s
ribosomes.
Virus
Consists of self-replicating molecule of DNA or RNA; has protective coat of protein
molecules; range from 20 nm to 300 nm in size; all viruses are parasitic because they
can only reproduce by taking over living cells.
Cell theory
The basic unit of structure and function of all living organisms is the cell.
Partially permeable membrane
An effective barrier between the cell and its surrounding materials. It allows a controlled
traffic of materials across it in both directions.
Freely permeable membrane
An ineffective barrier that would not keep anything out. Instead the chemicals of the cell
would simply mix with the surrounding chemicals by diffusion and nothing would exist.
Cell surface membrane
A very thin membrane (about 7 nm diameter) surrounding all cells; it is partially
permeable and controls the exchange of materials between the cell and its environment;
seen as having three layers (trilaminar appearance).
,Microvilli
Extensions of the cell surface membrane; used to increase surface area.
Microtubules
Make up cytoskeleton; made of tubulin.
Nucleus
A relatively large organelle found in eukaryotic cells, but absent from prokaryotic cells;
the nucleus contains the cell's DNA and therefore controls the activities of the cells.
Nuclear envelope
The two membranes surrounding the nucleus; the outer membrane of the nuclear
envelope is continuous with the endoplasmic reticulum.
Nuclear pores
Allow and control exchange between the nucleus and the cytoplasm.
Dna
Deoxyribonucleic acid; a molecule which contains the instructions that control the
activities of the cell.
Nucleolus
A small structure, one or more of which is found inside the nucleus; the nucleolus is
usually visible as a densely stained body; its function is to manufacture ribosomes using
the information in its own DNA.
Rough endoplasmic reticulum
Covered with ribosomes; proteins are often modified as they move through the rough
ER.
Ribosomes
Sites of protein synthesis; found in cytoplasm or on the rough ER.
Endosymbiont theory
Cytoplasmic ribosomes are 80s while those of bacteria, mitochondria and chloroplasts
are 70s.
,Cytoplasm
The contents of a cell, excluding the nucleus.
Smooth endoplasmic reticulum
Lacks ribosomes; makes lipids and hormones.
Lysosomes
Breakdown of unwanted structures; in white blood cells, lysosomes are used to break
down bacteria.
Oranelles
Functionally and structurally distinct parts of a cell.
Compartmentalism
Organelles themselves being surrounded by membranes so that their activities can be
separated from the surrounding cytoplasm.
Division of labour
Each type of organelle having its own function and therefore sharing the entirety of the
work between different specialized organelles.
Mitochondria
The organelle in eukaryotes in which aerobic respiration takes place; synthesizes lipids.
Golgi body
An organelle found in eukaryotic cells; the golgi apparatus consists of a stack of
flattened sacs, constantly forming at one end and breaking up into golgi vesicles at the
other end; golgi vesicles carry their contents to other parts of the cell, often to surface
membrane for secretion; the golgi apparatus chemically modifies the molecules it
transports; collects, processes, and sorts molecules (particularly proteins from Rough
ER).
Centriole
One of two small, cylindrical structures, made from microtubules, found just outside the
nucleus in animal cells, in a region known as the centrosome they are also found in the
bases of cilia and flagella.
, Centrosome
Assemble microtubules during nuclear division.
Cell wall
A wall surrounding prokaryote, plant and fungi cells; the wall contains a strengthening
material which protect the cell from mechanical damage, supports it and prevents it from
bursting by osmosis if the cell is surrounded by a solution with higher water potential.
Plasmodesmata
A pore-like structure found in plant cell walls; plasmodesmata of neighboring plant cells
line up to form tube-like pores through the cell walls, allowing controlled passage of
materials from one cell to the other; the pores contain ER and are lined with the cell
surface membrane.
Vacuole
An organelle found in eukaryotic cells; a large, permanent central vacuole is a typical
feature of plant cells, where t has a variety of functions, including storage of
biochemicals such as salts, sugars and waste products; temporary vacuoles(also known
as phagocytic vessels), may form in animal cells.
Tonoplast
A membrane surrounding the plant vacuole which controls exchange between the
vacuole and the cytoplasm.
Grana
A stack of circular thylakoids in a chloroplast.
Chloroplast
A photosynthetic organelle in eukaryotes; manufactures ATP from ADP.
Chlorophyll
A green pigment responsible for light capture in photosynthesis in algae and plants
Calculating microscopy
I/(a*m) i=image; a=actual; m=magnification
Terms with Certified Solutions 2023-2024
Eukaryote
Organisms who possess nuclei; includes plants, animals, fungi and unicellular
organisms known as protoctists; DNA is linear and bound to proteins to form chromatin.
Prokaryote
Organisms that lack nuclei; usually 1000 x - 10000 x smaller in volume than eukaryotes;
DNA is circular and free in the cytoplasm; known as simplest cells; contain 70s
ribosomes.
Virus
Consists of self-replicating molecule of DNA or RNA; has protective coat of protein
molecules; range from 20 nm to 300 nm in size; all viruses are parasitic because they
can only reproduce by taking over living cells.
Cell theory
The basic unit of structure and function of all living organisms is the cell.
Partially permeable membrane
An effective barrier between the cell and its surrounding materials. It allows a controlled
traffic of materials across it in both directions.
Freely permeable membrane
An ineffective barrier that would not keep anything out. Instead the chemicals of the cell
would simply mix with the surrounding chemicals by diffusion and nothing would exist.
Cell surface membrane
A very thin membrane (about 7 nm diameter) surrounding all cells; it is partially
permeable and controls the exchange of materials between the cell and its environment;
seen as having three layers (trilaminar appearance).
,Microvilli
Extensions of the cell surface membrane; used to increase surface area.
Microtubules
Make up cytoskeleton; made of tubulin.
Nucleus
A relatively large organelle found in eukaryotic cells, but absent from prokaryotic cells;
the nucleus contains the cell's DNA and therefore controls the activities of the cells.
Nuclear envelope
The two membranes surrounding the nucleus; the outer membrane of the nuclear
envelope is continuous with the endoplasmic reticulum.
Nuclear pores
Allow and control exchange between the nucleus and the cytoplasm.
Dna
Deoxyribonucleic acid; a molecule which contains the instructions that control the
activities of the cell.
Nucleolus
A small structure, one or more of which is found inside the nucleus; the nucleolus is
usually visible as a densely stained body; its function is to manufacture ribosomes using
the information in its own DNA.
Rough endoplasmic reticulum
Covered with ribosomes; proteins are often modified as they move through the rough
ER.
Ribosomes
Sites of protein synthesis; found in cytoplasm or on the rough ER.
Endosymbiont theory
Cytoplasmic ribosomes are 80s while those of bacteria, mitochondria and chloroplasts
are 70s.
,Cytoplasm
The contents of a cell, excluding the nucleus.
Smooth endoplasmic reticulum
Lacks ribosomes; makes lipids and hormones.
Lysosomes
Breakdown of unwanted structures; in white blood cells, lysosomes are used to break
down bacteria.
Oranelles
Functionally and structurally distinct parts of a cell.
Compartmentalism
Organelles themselves being surrounded by membranes so that their activities can be
separated from the surrounding cytoplasm.
Division of labour
Each type of organelle having its own function and therefore sharing the entirety of the
work between different specialized organelles.
Mitochondria
The organelle in eukaryotes in which aerobic respiration takes place; synthesizes lipids.
Golgi body
An organelle found in eukaryotic cells; the golgi apparatus consists of a stack of
flattened sacs, constantly forming at one end and breaking up into golgi vesicles at the
other end; golgi vesicles carry their contents to other parts of the cell, often to surface
membrane for secretion; the golgi apparatus chemically modifies the molecules it
transports; collects, processes, and sorts molecules (particularly proteins from Rough
ER).
Centriole
One of two small, cylindrical structures, made from microtubules, found just outside the
nucleus in animal cells, in a region known as the centrosome they are also found in the
bases of cilia and flagella.
, Centrosome
Assemble microtubules during nuclear division.
Cell wall
A wall surrounding prokaryote, plant and fungi cells; the wall contains a strengthening
material which protect the cell from mechanical damage, supports it and prevents it from
bursting by osmosis if the cell is surrounded by a solution with higher water potential.
Plasmodesmata
A pore-like structure found in plant cell walls; plasmodesmata of neighboring plant cells
line up to form tube-like pores through the cell walls, allowing controlled passage of
materials from one cell to the other; the pores contain ER and are lined with the cell
surface membrane.
Vacuole
An organelle found in eukaryotic cells; a large, permanent central vacuole is a typical
feature of plant cells, where t has a variety of functions, including storage of
biochemicals such as salts, sugars and waste products; temporary vacuoles(also known
as phagocytic vessels), may form in animal cells.
Tonoplast
A membrane surrounding the plant vacuole which controls exchange between the
vacuole and the cytoplasm.
Grana
A stack of circular thylakoids in a chloroplast.
Chloroplast
A photosynthetic organelle in eukaryotes; manufactures ATP from ADP.
Chlorophyll
A green pigment responsible for light capture in photosynthesis in algae and plants
Calculating microscopy
I/(a*m) i=image; a=actual; m=magnification
