CELL BIOLOGY #2 Flashcards
what happens in the mitochondria
mitochondria is where respiration takes place
what are chromosomes made of
DNA
what controls the rate of chemical reactions in the cytoplasm
enzymes
Oxygen is taken into cells by the process of?
diffusion
Cells need oxygen for?
respiration
the parts of cells that use up the most oxygen are the?
Mitochondria
Some cells produce oxygen in the process of
Photosynthesis
the process by which these gases move into and out of the cell is?
Diffusion
The diagrams show what happens to the shape of a plant cell placed in distilled water. Explain why the cell swells and becomes turgid. Name the process involved.
water molecules enter the cell by osmosis
Give one feature of the cell wall which allows the cell to become turgid
It is elastic
Describe the change which will occur if a piece of peeled potato is placed in a concentrated sugar
solution and explain why this change occurs
The piece of potato will shrink because the concentration of sugar is more than the concentration inside the cell therefore water is drawn out of the cell
explain why The barley roots were able to take up more sulfate ions with oxygen than without oxygen.
uptake by active transport ,requires energy more energy from aerobic respiration- there is more energy when oxygen is present
How do microvilli and mitochondria help in the active transport of the products of digestion from the small intestine into the blood?
microvilli– large(r) surface area
mitochondria- releases energy
Describe two features of the villi which help the small intestine to function.
Large Surface Area- digested food is absorbed quicker
single layer of surface cells
Explain the significance of the nucleus in determining the characteristics of the offspring.
the nucleus contains DNA which contributes to half the genes to the offspring
Explain one way in which the structure of the leaf mesophyll cell helps it to carry out its job
has chlorophyll/chloroplasts
to absorb light/produce food
name the chemical tthat makes the xylem rigid
lignin
what is diffusion
is the spreading out of particles of a gas or any substance in a solution
what determines the net movement of particles across a cell membrane
the concentration of particles on each side of the membrane
what is osmosis
the diffusion of water across a partially permeable membrane from a region of higher water concentration to a region of lower water concetration
isotonic meaning
if the two solutions are the same concentrations
hypertonic meaningq
a solution that is more concentrated than the cell contents(more solute)
hypotonic
the solution that is less concentrated than the cell contents (less solute)
what happens to animal cells in a hypotonic solution
they will swell and may burst as water moves in via osmosis
what happens to the animals cell if the solution is hypertonic
water moves out of the cell and it shrinks
when does turgor pressure occur in a cell
when no more water can enter a cell due to the pressure inside it
how can cells be kept rigid
as long as the outside solution is hypotonic water moves into the cell and keeps them rigid
what happens to plant cells in a hypertonic solution
they lose water and become flaccid so the plant wilts
what is plasmolysis
when the membrane pulls away from the cell wall due to plant cells being put in a hypertonic solution
what is active transport
movement of substances against a concentration gradient
where does active transport acquire its energy from
respiration
why does active transport need energy
to move substances against a concentration gradient
what is the difference between diffusion and osmosis
diffusion is the movement of all types of particle from a region of higher to lower concentration
osmosis is the movement of water from a dilute solute solution to a more concentrated solute solution across a partially permeable membrane
what are the features of a efficient exchange surface
large surface area
thin walls or short diffusion path
good transport system
difference between diffusion and active transport
active transport requires energy and in active transport the movement of particles is against the concentration gradient
diffusion does not require energy and in active transport particles move down the concentration gradient
example of active transport in plants
example in a human
absorption of mineral ions by roots
absorption of glucose out of the gut or from kidney tubules in the blood
explain in detail what happens to plant cells in a hypertonic solution
water moves out of the cell from a more dilute to the more concentrated solution
the vacuole and the cytoplasm shrink
so the cell membrane draws away from the cell wall and becomes plasmolysed
explain why animals that normally live in fresh water may die if placed in sea water
sea water contains salt
so the solution around the animal is hypertonic to its cells
water leaves the cells so chemical reactions in the cytoplasm stops
what is turgor pressure and why is it important
when water enters the vacuole in a plant cell creating a pressure called turgor pressure
the cell becomes rigid and this helps to support the plant
as organisms increase in size
their surface area to volume ratio decreases
why do large organisms need a specialised exchange surfaces
large organisms have a small surface area to volume ratio exchange surfaces allow materials to be passed to a transport system which carries them to all cells
how are leaves adapted to increase their surface area
leaves are flat and thin and have internal air spaces and stomata
what does more concentrated mean (osmosis)
less water
what does dilute mean (osmosis)
more water
function of muscle cells in the wall of the body
they contract to churn food
why did the students dry the potato before weighing it``
so that any change in mass was not due to the water on the outside of the potato
