B1 Cell Biology Flashcards
What is diffusion?
The spreading out of particles with a net movement from a high concentration to a low concentration
Why is oxygen needed in the body?
It is needed for respiration in cells
Why does oxygen move into a cell?
There is a high concentration outside the cell as it is surrounded by blood from the lungs.
Why does carbon dioxide move out of the cell?
There is a high concentration of carbon dioxide in the cell
What is carbon dioxide in the body?
A waste product of respiration
What is urea?
A waste product produced in cells
Why does urea move out of the cell?
There’s a high concentration in the cell so if users through the membrane into blood plasma
What factors increase the rate of diffusion?
A higher surface area
A greater concentration gradient
High temperature
What is surface area to volume ratio?
A measure of how large an organism surface area is compared to its volume.
Why can single celled organisms use diffusion to get all the gases?
They have a large surface area to volume ratio
What happens when an organisms gets larger?
Surface area to volume ratio falls
Why can multicellular organisms not use diffusion to get gases?
The surface area to volume ratio is not large enough so oxygen cannot diffuse to the centre of the organism
What adaptation do gills have?
Large surface area
Thin membrane
High blood flow
What is osmosis?
The movement of water molecules over a partially permeable membrane from an area of high concentration to an area of low concentration
What is active transport?
The movement of particles against concentration gradient using energy transferred during respiration
How do plants use active transport?
It allows minerals in areas of low concentration in the soil to move into the root hair cells against a concentration gradient
How is active transport used in digestion?
When there is a low concentration of nutrients in the gut but higher concentration of nutrients in the blood.
What is the difference between active transport and diffusion?
Active transport uses energy while diffusion is passive.
How are alveoli adapted for gas exchange?
Large surface area
Moist lining for dissolving gases
Very thin walls
Good blood supply
What are villi?
Tiny projections in the small intestine to help absorb digested food as quickly as possible
What are the adaptations of villi?
Single layer of surface cells
Very good blood supply to assist quick absorption
What adaptations do leaves have?
Stomata
Oxygen and water diffuse out of the stomata
Flatten shape to increase area of exchange surface
Air spaces inside the leaf
What is a prokaryotic cell?
A smaller and simpler cell compared to a eukaryotic cell
What is a eukaryotic cell?
A complex cell including all animal and plant cells.
What structures do bacterial cells have?
Strands of DNA
Plasmids
No chloroplast or mitochondria
Cell wall
What are the parts of a microscope?
Eyepiece Coarse adjustment knob Fine adjustment knob Light Stage High and low power objective lenses
what is 1 order of magnitude mean?
It means 10x
every order of magnitude is 10 times greater than the one before.
what are mitochondria?
where aerobic respiration takes place
what are ribosomes?
the site of protein synthesis
what other structures do plants cells contain?
chloroplasts
cell wall
vacuole
what are chloroplasts?
they contain chlorophyll and are the site of photosynthesis
what is the cell wall?
it is made of cellulose and strengthens the cell
what is the vacuole?
a sac filled with cell sap which helps give the cell shape
what is specialisation?
when a cell has adaptations which help them to carry out their particular function
what adaptations do sperm cells have?
a long tail - allows it to swim, makes it streamlined
packed with mitochondria - provide the energy to swim
contain enzymes - allows the sperm to digest the outer layer of the ovum
what are the adaptations of a muscle cell?
protein fibres - can change length to allow cells to contract
mitochondria - provides energy for muscle contraction
what are the adaptations of a nerve cell?
an axon - carries the electrical impulses
myelin sheath - insulates axon to speed up transmission
synapses - allow impulses to pass between cells
dendrites - increase surface area so other nerve cells can connect more easily
why do plant roots have root hairs?
to increase the surface area of the root so it can absorb water and dissolved minerals more easily
what adaptations do root hair cells have?
root hair - increases surface area
no chloroplasts - cells are underground
what adaptations do xylem cells have?
lignified walls - provide support
broken down end walls - water can flow easily
no internal structures - makes it easy for water to flow
what adaptations do phloem cells have?
sieve plates - allow dissolved sugars to move through the plant
companion cells - provide energy for the vessel cell
what are some limitations of light microscopes?
limited magnification
limited resolution
what are some advantages of an electron microscope?
greater magnification and resolution
what is the formula for calculating magnification?
magnification = size of image/real size of object
what is meant by turgid?
when water moves into the cell by osmosis and becomes swollen. it does not burst as the cell wall supports the cell
what does flaccid mean?
when water moves out of a plant cell by osmosis and causes it to shrink
what is a concentration gradient?
the difference between the areas of high concentration and low concentration
