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
what are the disadvantages of adult stem cells?
- risk of infection
- can only treat a few diseases
- procedure can be painful
describe therapeutic cloning
- a body cell is taken from the patient. the nucleus is separated from the cell
- the nucleus from the patient is fused with an empty egg cell from the donor
- the cells are stimulated to divide and develop into an embryo
- stem cells are available for therapeutic use
what are uses of cloning plants?
- rare species can be cloned to protect from extinction
- crop plants with special features such as disease resistance can be cloned to produce large numbers of identical plants for farmers
describe how coronary heart disease occurs
- layers of fatty material build up inside the coronary arteries
- this reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle
describe what stents do
stents are used to keep the coronary arteries open
describe what statins do
used to reduce blood cholesterol levels which slows down the rate of fatty material deposit
how can faulty heart valves be replaced?
valves can be replaced using biological or mechanical valves
describe a way to treat heart failure
a donor heart, or heart and lungs can be transplanted
what are artificial hearts used for?
are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery
describe the process of binary fission
- cells divide into two
- circular strand of DNA replicate
- circular strands migrate to opposite ends of the cell
- cytoplasm replicates and divides into two
- two identical daughter cells are formed- identical to the parent
what are the uses of monoclonal antibodies?
- detecting illnesses e.g. prostate cancer, covid
- treating illnesses e.g. cancer
how is a sporozoite formed and what do they do?
- sporozoite are formed when plasmodium parasites reproduce sexually
- they then travel to the mosquitoes salivary glands
- so when the mosquito bites another human, the sporozoite is injected into them
how are merezoites formed and what do they do?
- the sporozoites travel to the liver where they multiply asexually inside the live cells
- which form merozoites that then inject the red blood cells
how are schizonts formed and what do they do?
- some of the merozoites turn into a new form called schizonts
- which then burst open the red blood cells
- that causes raging fever and exhausting sweats
why is malaria difficult to treat?
- the disease has many different phases when the parasites are in the bloodstream
- most drugs only target one form of the parasite and would leave other forms untouched
what are drugs?
a chemical that alters the way in which your body works
describe the plant, the drug and what they’re used to treat
- foxgloves - digitalis - used to treat heart conditions
- willow bark - aspirin - used as a painkiller and to lower fever
- penicillum mould - penicillin - bacterial injections
why do we need to test a drug?
we test for efficiency - it must prevent or cure a disease or at least make you feel better
why do we test for toxicity?
the drug must not be too toxic (poisonous) or have unacceptable side effects for the patient
why do we test to get the dose right?
so we know how much is needed for it to work
what is a pre-clinical trial?
a trial that involves testing on cells and tissues to test if the drug is toxic
what is a clinical trial?
when human volunteers (who are healthy) are first used to test for toxicity
what are blind trials?
patients do not know which drugs they are taking - a real drug or a ‘placebo’ (a dummy drug)
what are double blind trials?
neither the doctors or the patients know if they are taking the real drug (this prevents bias)
what are the physical plant defences?
- waxy cuticle prevents pathogens from entering
- cellulose cell walls prevent pathogens from entering
- layers of dead cells around stems that prevent pests from entering the living cell underneath e.g. bark on trees
what are the mechanical plant defences?
- mimosa stems are sensitive to touch - they will droop or curl when touched, can be hard for insects to hang on
- thorns and hairs: stops animals from landing and eating the plant
- mimicry: has features that trick animals into not feeding or laying eggs
what are the chemical plant defences?
- production of antibacterial chemicals
- production of poisons to deter herbivores
- deadly nightshade produces a poison called atropine
- witch hazel plant - produces an antiseptic and used often in beauty products
describe what happens when light intensity increases for photosynthesis
- as light intensity increases, the rate of photosynthesis increases until the line plateaus and the rate remains constant
- this is because temperature or CO2 is now a limiting factor
describe what happens when CO2 concentration increases for photosynthesis
- as carbon dioxide concentration increases
- the rate of photosynthesis increases until the line plateaus and the rate remains constant
- this is because temperature or light intensity is now a limiting factor
describe what happens when temperature increases for photosynthesis
- as temperature increases
- the rate of photosynthesis increases, but decreases again at really high temperatures
- this is because the enzymes in the plant are denatured
what can glucose be stored as?
starch
protein
cellulose
lipids
what are the 6 main uses of glucose?
starch
cellulose
amino acids (proteins)
respiration
fats and fructose
how is starch made from glucose?
glucose is turned into lipids for story in seeds, seeds also store starch
how are proteins made from glucose?
glucose is combined with nitrates to make acids, which are then made into proteins
how is cellulose made from glucose?
glucose is converted into cellulose for making cell walls, especially in a rapidly growing plant
how are lipids made from glucose?
glucose is turned into lipids
what is the equation for anaerobic respiration in animals?
glucose —> Lactic acid + (a little bit of energy)
what is the equation for respiration in plants and yeast?
Glucose —> ethanol + carbon dioxide
describe the differences between aerobic and anaerobic respiration
aerobic:
has oxygen
produces carbon dioxide and water
water produced
carbon dioxide produced
glucose used
lots of energy produced
anaerobic:
no oxygen
produces ethanol and carbon dioxide
no water produced
CO2 produced (only in plants + fungi)
glucose used
some energy produced
used in fermentation, alcohol produced
what is fermentation?
in plant and yeast cells, anaerobic respiration is different to the creation which occurs in our muscles
what is metabolic rate?
the speed at which chemical reactions take place in the body
what does metabolism include?
- conservation of glucose to starch, glycogen and cellulose
- the formation of lipid molecules from a molecule of glycerol and three molecules of fatty acids
name factors that affect metabolic rate
age
gender
inherited factors
body size/ weight
- exercise levels
- proportion of muscle to fat
- pregnancy
what happens in your body during exercise?
- the heart beats faster to deliver more oxygen and glucose to the cells
- the cells are respiring more as the muscles need more energy
- breathing rate also increases as more oxygen is needed
why are breathing and heart rates still high even after exercise
to repay the oxygen debt
oxygen must oxidise the lactic acid formed from anaerobic respiration
what are the advantages of statins?
advantages:
- statins can reduce the risk of strokes, coronary heart disease and heart attacks
- can increase the amount of beneficial type of cholesterol (known as ‘good’ cholesterol or HDL cholesterol) in your bloodstream
- some studies suggest that statins may also help prevent some other diseases
what are the disadvantages of statins?
- statins are a long-term drug that must be taken regularly
- statins cause sometimes cause negative side effects
- the effect of statins isn’t instant - it takes time for their effect to kick in
describe the type of pathogen, the symptoms, the mode of transmission, prevention and treatment for measles
- virus
- fever, skin rash, infertility
- air droplets in sneezes
- vaccine
- none - drink fluids and rest
describe the type of pathogen, the symptoms, the mode of transmission, prevention and treatment for HIV
- virus
- fever, headache, muscle ache
- unprotected sex, sharing needles
- use condoms
- antiretroviral drugs
describe the type of pathogen, the symptoms, the mode of transmission, prevention and treatment for tobacco mosaic virus
- virus
- stunting, yellow spotting on leaves, mosaic pattern of light and dark green
- when an infected leaf rubs against a leaf of a healthy plant, by contaminated tools, smoking
- avoid handling plants, removed diseased plants, control weeds and rotate crops
- dig up and destroy infected plants, wash hands after handling infected plants
describe the type of pathogen, the symptoms, the mode of transmission, prevention and treatment for salmonella
- bacteria
- diarrhoea, fever, stomach cramps
- contaminated food or water
- wash hands, surfaces cook food properly
- drink plenty, antibiotics
describe the type of pathogen, the symptoms, the mode of transmission, prevention and treatment for gonorrhoea
-bacteria
- pain when weeing, green discharge
- unprotected sex
- use condoms
- antibiotics
describe the type of pathogen, the symptoms, the mode of transmission, prevention and treatment for rose black spot
- fungus
- black spots on leaves
- water and direct contact
- remove infected leaves
- fungicides
describe the type of pathogen, the symptoms, the mode of transmission, prevention and treatment for athletes foot
- fungus
- red, itchy flaky skin
- touching infected skin or surfaces
- keep feet dry, don’t share towels
- anti-fungal medicine
