b1 Flashcards
define eukaryotic
contains genetic material (DNA) in a nucleus
define prokaryotic
does not contain genetic material (DNA) in a nucleus
what does an animal cell contain?
cell membrane, cytoplasm nucleus and mitochondria
what does a plant cell contain?
cell membrane, cytoplasm, nucleus, mitochondria, cell wall, chloroplast and vacuole
is a bacterial cell prokaryotic or eukaryotic?
prokaryotic
is a yeast cell prokaryotic or eukaryotic?
eukaryotic
what does a bacterial cell contain?
cell membrane, cytoplasm, plasmids (rings of DNA), cell wall, slime capsule and flagella
what does a yeast cell contain?
cell membrane, cytoplasm, nucleus and cell wall
what is the function of a nucleus?
contains genetic material and controls the cell’s activities
what is the function of a cytoplasm?
where chemical reactions take place
what is the function of a cell membrane?
controls the movement of substances in and out of the cell
what is the function of a mitochondria?
where lots of energy is released by respiration
what is the function of a ribosome?
where protein synthesis takes place
what is the function of a cell wall?
provides strength to the cell
what is the function of a chloroplast?
contains chlorophyll to absorb light for photosynthesis
what is the function of a vacuole?
contains chemicals and cell sap to keep the cell turgid
define magnification
the ability to make small objects seem larger
name two types of microscopes
electron and light microscope
define resolution
the ability to distinguish two objects from each other
why is the electron microscope better than the light microscope?
it has a higher magnification and resolution
what is the magnification equation?
magnification = image size / real size
how do you convert mm to micrometres?
X 1000
what does the coarse focusing wheel do?
it brings the object into near focus
what does the fine focusing wheel do?
it brings the object in detail
what does the objective lens do?
it determines the level of magnification for the object
state the three structures of mitosis
nucleus, chromosome and gene
how many chromosomes in a body cell?
46 chromosomes
how many chromosomes in a sex cell?
23 chromosomes
what is a haploid?
a cell that has half the number of chromosomes
what is a diploid?
a cell that has two copies of genetic material
why is mitosis important?
- for growth and development of multicellular organisms
- takes places when an organism repair itself
- happens during asexual reproduction
what is the first stage of mitosis?
- the cell grows
- it increases in the number of organelles
- DNA replicates
what is the second stage of mitosis?
- the chromosomes are pulled apart to each
end of the cell - the nucleus divides
what is the third stage of mitosis?
the cytoplasm and cell membrane
divide to form 2 genetically identical
cells.
what is a stem cell?
an undifferentiated cell that has the ability to specialise into any type of cell
name the three type of stem cells?
- embryonic
- adult
- plant
state the function of each stem cell
embryonic - can differentiate into any cell
plant - can differentiate into any cell
adult - can only differentiate in blood cells
where are plant stem cells located?
meristem
what 2 conditions do stem cells help with?
- type 1 diabetes
- paralysis
what is therapeutic cloning?
when an embryo is produced with the same genes as the individual
state advantages and disadvantages of therapeutic cloning
+ cures medical conditions
+ it is not rejected by the body’s immune system
- potential life is killed (ethical issue)
- shortage of doners
state advantages and disadvantages of using stem cells from plants
+ can treat an untreatable condition
+ allow further studies into developing new theories
- success is not guaranteed
- finding doners can be difficult
define diffusion
particles moving from a high concentration to a low concentration
how are surfaces adapted for efficient gas exchange?
- large surface area of the membrane
- concentration gradient
- temperature
define osmosis
water particles moving from a high concentration to a low concentration, through a partially permeable membrane
what is a partially permeable membrane?
only allows water molecules through
define active transport
particles moving from a low concentration to a high concentration, using energy from respiration
where does active transport occur?
mitochondria, as lots of energy is needed
what does a specialised cell mean?
it has a specific adaptation to do a specific job
state the function of a sperm cell
toswim to the egg and transfer genetic information - fertilise with egg cell
state the adaptations of a sperm cell
- the head contains enzymes to help break down the egg
- the midpiece contains lots of mitochondria = lots of energy to swim faster
- the tail helps the sperm swim
state the function of a nerve cell
sends electrical impulses around the body
state the adaptations of a nerve cell
- the dendrites (branches) give a large surface area to connect with other nerve cells
- the long axon carries electrical impulses for long distances
- the synapses (the end) allow the impulse to pass from one nerve cell to another.
state the function of a muscle cell
to contract and do movements
state the adaptations of a muscle cell
- protein fibres to help the muscles contract and relax (increase and decrease the length of a cell)
- lots of mitochondria to provide energy for muscle contraction
state the function of a root hair cell
absorbs minerals and water ions to the soil
state the adaptations of a root hair cell
- the root hair increases the surface area of the root
- does not contain chloroplasts as it is underground
state the function of a xylem
(transpiration - water is lost) transport water and mineral to the plant (leaves)
state the adaptations of a xylem
- the thick walls contain lignin to support the plant
- it is hollow making it easier for water and minerals to flow
state the function of a phloem
(translocation - food moves to different parts of a plant) transports dissolved sugars up and down the plant
state the adaptations of a phloem
- the sieve plates allow dissolved sugar to move
through the cell - there is lots of mitochondria to provide energy
- the phloem vessel cells have no nucleus and only limited by cytoplasm.
when can animal cells differentiate?
when they are young
when can plant cells differentiate?
throughout their life
what is cell division restricted to in animals?
repair and growth
state the microscopy practical
- Use a dropping pipette to put one drop of water onto a microscope slide.
- Separate one of the thin layers of the onion.
- Peel off a thin layer of epidermal tissue from the inner surface.
- Use forceps to put this thin layer on to the drop of water that you have placed on the microscope slide.
- Make sure that the layer of onion cells is flat on the slide.
- Put two drops of iodine solution onto the onion tissue.
- Carefully lower a coverslip onto the slide.
- Put the slide on the microscope stage
how do you set up the microscopy practical?
- Turn the nosepiece to the lowest power objective lens (X4)
- Turn the coarse adjustment knob so that the end of the objective lens is almost touching the slide.
- Now slightly rotate the fine adjustment knob to bring the cells into a clear focus.
- Now rotate the nosepiece to use a higher power objective lens.
- When you have found some cells, switch to a higher power.
