B1 - Key Concepts in Biology Flashcards
Define
subcellular structures.
the different parts of a cell
What is the role of the
nucleus?
contains genetic material that controls the activities of the cell
genetic material is arranged into chromosones
What is the
cytoplasm?
the gel-like substance where most of the chemical reactions happen, it contains enzymes that control these chemical reactions
What is the role of the
cell membrane?
holds the cell together and controls what goes in and out
What are the
mitochondria?
where most of the reactions for respiration take place
respiration transfers energy that the cell needs to work
What is the role of the
ribosomes?
be involved in the translation of genetic material in the synthesis of proteins
What is the role of the
cell wall?
And what is it made of?
it supports the cell and strengthens it
it is made of cellulose
What is the role of the
large vacuole?
it maintains the internal pressure to support the cell
it contains cell sap, a weak solution of sugar and salts
What is the role of the
chloroplasts?
where photosynthesis occurs, which makes food for the plant
they contain a green substance called chlorophyll
What subcellular structures are found in (most)
animal cells?
(5)
- nucleus
- cell membrane
- mitochondria
- ribosomes
- (cytoplasm)
What subcellular structures are found in (most)
plant cells?
(8)
- nucleus
- cell membrane
- mitochondria
- ribosomes
- cell wall
- large vacuole
- chloroplasts
- (cytoplasm)
What subcellular structures are found in (most)
bacterial cells?
(5)
- chromosonal DNA
- ribosomes
- cell membrane
- plasmid DNA
- flagellum
What is the role of the
chromosonal DNA
in bacterial cells?
controls the cell’s activities and replication, it floats free in the cytoplasm
(not a nucleus)
What are the
plasmid DNA
in bacterial cells?
small loops of extra DNA that aren’t part of the chromosone
What are the
flagellum
in bacterial cells?
long, hair-like structures that rotate to make the bacterium move
Define
specialised cell.
a cell that has a structure which makes them adapted to their function
What are the main functions of an
egg cell?
(2)
- carry the female DNA
- nourish the developing embryo in the early stages
How is an egg cell adapted to its function?
(3 things)
- it contains nutrients in the cytoplasm to feed the embryo
- it has a haploid nucleus
- straight after fertilisation, its membrane changes structure to stop any more sperm getting in
What is the function of
sperm?
transport the male’s DNA to the female’s egg
How is a sperm cell adapted to its function?
(4)
- it has a long tail so that it can swim to the egg
- it has lots of mitochondria in the middle section to provide the energy (from respiration) needed to swim this distance
- it has an acrosome at the front of the ‘head’, where it stores enzymes needed to digest its way through the membrane of the egg cell
- it contains a haploid nucleus
Define
resolution.
how well a microscope distinguishes between two points that are close together
What are the benefits of electron microscopes over light microscopes?
(3)
- higher magnification
- higher resolution
- let us see the internal structure of mitochondria and chloroplasts
How do you calculate
total magnification?
eyepiece lens magnification x objective lens magnification
What equation links
magnification, image size and actual size?
image size = actual size x magnification
Define
substrate.
the molecule changed in the reaction
Define
active site.
the part where an enzyme joins on to its substrate to catalyse the reaction
What factors affect
enzyme controlled reactions?
(3)
- temperature
- pH
- substrate concentration
What reaction does the enzyme amalyse catalyse?
the breakdown of starch to maltose
How would you calculate
rate of reaction?
change/time
What are
carbohydrases?
And what is an example?
enzymes which convert carbohydrates into simple sugars
e.g. amylase
What are
proteases?
enzymes which convert proteins into amino acids
What reaction does lipase catalyse?
the conversion of lipids into glycerol and fatty acids
What reaction does glycogen synthase catalyse?
the joining together of lots of chains of glucose molecules to make glycogen
Define
biological molecule.
a molecule that is found in a living organism
How would you test for
reducing sugars?
(4 steps)
- Add Benedict’s reagent (which is blue) to a sample
- Heat it in a water bath that’s set to 75°C
- If there are reducing sugars then a coloured precipitate will be formed
- The higher the concentration of reducing sugar, the further the colour change goes
blue -> green -> yellow -> orange -> brick red
How would you test for
starch?
(3 steps)
- Add iodine solution to the test sample
- If starch is present, the sample changes from browny-orange to a dark, blue-black colour
- If there’s no starch, it stays browny-orange
How would you test for
lipids?
(3 steps)
- Shake the test substance with ethanol for about a minute until it dissolves, then pour the solution into water
- If there are any lipids present, they will precipitate out of the liquid and show up as a milky emulsion.
- The more lipid there is, the more noticeable the milky colour will be
How would you test for
proteins?
(4)
- Add a few drops of potassium hydroxide solution to make the solution alkaline
- Then add some copper(II) sulfate solution (which is bright blue)
- If there’s no protein, the solution will stay blue
- If protein is present, the solution will turn purple
How would you calculate the total amount of energy in the food after calorimetry?
energy (J) = mass of water (g) x temperature change of water (°C) x 4.2
Define
diffusion.
the net movement of particles from an area of higher concentration to an area of lower concentration
Define
osmosis.
the net movement of water molecules across a partially permeable membrane from an area of higher water potential to an area of lower water potential
Define
active transport.
the movement of particles across a membrane against a concentration gradient using energy transferred during respiration
What is the formula for
percentage change (in mass)?
(final mass - initial mass) / inital mass
(x100)
