paper 1 Flashcards
Is a plant cell a prokaryotic cell or a eukaryotic cell?
eukaryotic
In which sub-cellular structures do most of the reactions of the aerobic respiration take place?
mitochondria
describe the main similarities and differences between a bacterial cell and a plant cell
similarities: both have a cell membrane, a cell wall and cytoplasm
differences: plant cells have chloroplasts and mitochondria but bacteria don’t
plant cells have a true nucleus, whereas bacteria have a single circular strand of DNA that floats freely in the cytoplasm
bacterial cells may also contain small rings of DNA
what are the functions of the cell membrane, nucleus and cytoplasm?
cell membrane ~ this holds the cell together and controls what enters and leaves
nucleus ~ this contains the genetic material that controls the activities of the cell
cytoplasm ~ this is a gel-like substance where chemical reactions happen. it contains enzymes that control these reactions
what are the stages of the cell cycle
stage 1:
DNA replicates
stage 2:
one set of chromosomes is pulled
stage 3:
the cytoplasm and cell membrane divides to form two cells
differences between the xylem and the phloem
xylem transports water and minerals
phloem transports sugars
xylem is made up of dead cells
phloem is made up of living cells
xylem cells do not have pores in their end walls
phloem cells do have pores in hair end walls
phloem contains cytoplasm
xylem does not contain cytoplasm
why was the rate of water loss in plants lower at night?
the stomata are almost completely closed because it’s cooler and there’s no sunlight
feature of a nerve cell
any from:
they’re long
has branches
has insulation
features of red blood cells
have no cell wall
has no chloroplasts
do not contain chlorophyll
doesn’t contain a nucleus
are much smaller than plant cells
describe how the nerve cell is adapted to increase the absorption of substances from the soil
has a large surface area
what is the function of the fine adjustment knob?
to focus
suggest one reason why someone won’t be able to see cells through looking through the eye piece
there’s no cells in the field of view
why does a red blood cell burst in water and a plant cell doesn’t?
water enters plant cells by osmosis, plant cells have a cell wall to prevent them from bursting
describe the cell cycle
- the cell grows and DNA is replicated (increase in sub cellular structures)
- copies of chromosomes are then pulled apart to opposite sides of the cell, the nucleus divides
- the cytoplasm and cell membrane also divide to form 2 identical daughter cells
what is the structure and function of the stomata?
stomata allows gas to move into and out of the leaf
CO2 can diffuse into the leaf for photosynthesis
describe how water exits the plant
- water exits the plant via evaporation at the stomata
where is stomata found?
stomata are found on the bottom of the leaf - they are less exposed to the sun and there is less evaporation
describe the structure and the function of the upper epidermis
thin + transparent, allows more light to reach photosynthesising cells
describe the structure and the function of the lower epidermis
has pores called stomata
stomata allows gas to move in and out of the leaf
describe the structure and the function of the palisade mesophyll
tightly packed and contains many chloroplasts
allows to photosynthesise more efficiently
describe the structure and the function of the spongy mesophyll
has lots of air spaces
allows gases to diffuse into and out of the leaf
CO2 can diffuse in for photosynthesis
what is the job of the leaf and what does it need in order to carry out its job?
the leaf’s job is to produce glucose in photosynthesis, it needs:
sunlight
carbon dioxide
water
describe how mineral ions enter the plant
- mineral ions (magnesium and nitrogen ions) enter the plant at the roots
- mineral ions move from the soil into the hair cell via active transport
- move against the concentration gradient
describe how the structure of root hair cells help to carry out its function
- root hair cells have lots of mitochondria which release energy for active transport of mineral ions
- have adaptations to make the movement of substances in the root more efficient
- have a large surface area
describe the process of transpiration in plants
- water is transported by xylem vessels (dead cells)
- water only moves upwards
- xylem vessels have no walls between cells so water can move
- the walls of xylem are strengthened by lignin
describe the process of translocation in plants
- sugar is needed by all cells in the plant so they can respire
- sugar is transported by the phloem vessels (living cells)
- sugar moves in both directions
describe how phloem cells are adapted to transport sugar
- cells are elongated
- cell sap can move between cells via pores in the end walls
what are the factors that affect transpiration and describe how it affects the rate
temperature - increase rate - increases rate of evaporation
wind speed - increases rate - increases rate of evaporation
light intensity - increases rate - stomata open wider to allow CO2 to enter the leaf in photosynthesis
humidity - decreases rate - moist air surrounds stomata so decreases rate of evaporation
what are the factors that affect active transport?
- temperature - higher the temperature, the higher the rate of
- difference in concentration - the bigger the difference, the higher the rate
- surface area to volume ratio - the bigger the surface area to volume ratio, the higher the rate
- diffusion distance - the shorter the diffusion distance, the higher the rate
what are 3 common adaptations of the human alveoli and the fish lamellae?
- thin walls
- good blood supply to maintain concentration gradient
- large surface area to volume ratio
describe how the body reacts to when a vaccine is injected into your body
- a weakened version of the virus is injected into your body
- the white blood cells sees the weakened virus as foreign and engulfs and digests the pathogen
- the white blood cells then produce antibodies to help kill the pathogen
- memory cells are also produced and stay in the body
- so when exposed to the virus again, the white blood cells will produce antibodies more rapidly
- the white blood cells also produce anti-toxins to neutralise the toxins found in the pathogen
what is the function of embryonic stem cells?
can differentiate into all types of cells, taken from embryos
what is the function of adult stem cells?
can differentiate into certain type of cells e.g. blood cells, taken from bone marrow of adults
what are the advantages of embryonic stem cells?
- can be used to cure certain diseases/ illnesses e.g. cancer
- create many embryos in lab or come from donated embryos
- painless technique
- treat many diseases
- become any type of cell
what are the disadvantages of embryonic stem cells?
- expensive
- ethical issues
- it’s new, so we don’t have enough knowledge on it
- destroys embryo
- rights for embryos/ embryo cannot consent
- unreliable
- cancer
what are the advantages of adult stem cells?
- no ethical issues
- can treat some diseases
- procedure is (relatively) safe
- reliable technique
- quick recovery