Studied by 3 peopleCell
smallest unit of life
Eukaryotic cells
more complex cells, part of multicellular organisms
Prokaryotic cells
simpler cells, bacterial cell
Prokaryote
a unicellular organism
Eukaryote
an organism made from eukaryotic cells
What are the 2 types of eukaryotic cells?
animal and plant
Nucleus
controls the cell and contains genetic material
Cytoplasm
substance in which most chemical reactions happen
Cell membrane
controls substances that enter and exit the cell
Mitochondria
where aerobic respiration takes place
Ribosomes
site of protein synthesis
Cell wall
supports and protects cell, made of cellulose
Vacuole
contains cell sap
Chloroplasts
site of photosynthesis, contains chlorophyll
Which feature do plant cells have that animal cells don't?
cell wall, chloroplasts, vacuole
What are the 2 types of microscope?
light and electron
What is the formula for magnification?
magnification = image size / actual size
1mm = ?μ ?
1000
Specialised cells
Cells that are adapted to carry out a specific function
Differentiation
process of a cell becoming specialised
What a sperm cells specialised for?
reproduction
What are the adaptions of a sperm cell?
streamlined, tail, lots of mitochondria, enzymes
Why does sperm have a streamlined shape and tail?
to help it swim
Why does sperm have lots of mitochondria?
to have lots of energy to reach egg
Why does sperm have enzymes in its head?
to break enamel of egg
What is a nerve signal specialised for?
rapid signalling
What is the adaption of a nerve cell?
long
Why are nerve cells long?
to carry electrical signals all around the body
What is the adaption of a muscle cell?
lots of mitochondria
Why does a muscle cell have lots of mitochondria?
to have enough energy to contract quickly
What is a root hair cell specialised for?
Absorbing water and minerals
What is the adaptation of a root hair cell?
large surface area
Why does a root hair cell have a large surface area?
to absorb large amounts of water and minerals
Mitosis
the process of eukaryotic cell division when the cells divide
What processes must happen before mitosis?
increase number of subcellular structure, duplicate DNA
Binary fission
the process of prokaryotic cell division
What are good conditions for bacteria reproduction?
warm, lots of nutrients
Culture medium
a nutrient solution or agar jelly in/on which bacteria in cultured
How are agar plates made?
agar jelly poured into Petri dish, microorganisms added to the plate, bacteria multiplies
How are microorganisms added to the plate?
innoculating loop or pipette and spreader
In school what is the max temp. agar plates are kept at?
25°C
Why are agar plates not kept above 25°C?
In case harmful pathogens are produced
How can the effect of antibiotics on bacterial growth be investigated?
soaking paper discs in antibiotics, adding to an agar plate, left for 48hrs, measure diameter of inhibition zone
How can the conditions be regulated?
aseptic method
stem cells
undifferentiated cells
What are the 2 types of stem cell?
adult, embryonic
embryonic stem cell
stem cells able to differentiate into any type of cell
adult stem cell
stem cells able to differentiate into 1 type of cell
Give 3 examples of where adult stem cells are found?
bone marrow, brain, hair
What do adult stem cells in the bone marrow make?
blood cells
Therapeutic cloning
producing embryonic cells with the same genetic information as the patient
Pros of therapeutic cloning
replace faulty cells, body will not reject transplanted cells
Cons of therapeutic cloning
risk of contamination, ethics
Where are stem cells found in plants?
meristems
How can plant stem cells be used in agriculture?
develop drought, flood, disease resistant crops
Diffusion
movement of particles from a higher to a lower concentration
concentration gradient (diffusion)
different between concentrations
osmosis
diffusion of water
active transport
absorption of a substance against the concentration gradient (low
Where do plants get energy for active transport from?
respiration
Where do humans get energy for active transport from?
glucose from gut or kidneys
How is active transport used in digestion?
transport glucose from small intestine to bloodstream
Why is a large surface to volume ratio important?
to absorb or exchange the most substance
exchange surface
surface where substances are exchanged
How are alveoli adapted for gas exchange?
large surface area, blood supply, thin walls, moist lining
Why do alveoli have a moist surface?
to help dissolve gases to exchange them quicker
How is the small intestine adapted for diffusion and active transport?
villi, single cell walls, capillaries
How is a leaf adapted for gas exchange?
flattened shape, stomata, guard cells, air space
Why do leaves' flattened shape help gas exchange?
large surface area
How do guard cells help gas exchange?
control stomata
Why do stomata help gas exchange?
to close when to much water vapour is lost
How does air space in leaves help gas exchange?
more space for gases to enter leaf
Where is a leaf's exchange surface?
lower epidermis
What is the exchange surface on a fish?
gills
How do gills work?
water enters through the mouth and out the gills, oxygen diffuses into gills and carbon dioxide out
What makes gills good at exchanging substances?
gill filaments covered in lamellae - large surface area
lots of capillaries - good blood supply
thin surface area - easy diffusion
blood and water flow in opposite directions - high concentration gradient
turgor pressure
pressure created by vacuole against cell wall
Note
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