year 10 eoy exam Flashcards
what are the characteristics of living organisms?
MRS H GREN
Movement
Respiration
Sensitivity (they respond to their surroundings)
Homeostasis (maintaining internal conditions)
Growth
Reproduction
Exretion
Nutrition
are plants multicellular?
yes
what are the cell walls of plants made of?
cellulose
what do plants store carbohydrates as?
starch or sucrose
what are some examples of plants?
maize, peas, beans
are animals multicellular?
yes
can animals photosynthesise?
no
what do they store carbohydrates as?
usually glycogen
do animals have nervous coordination?
yes, and they an move from one place to another
what are some examples of animals?
humans, tigers, dogs, houseflies, spiders
are fungi able to photosynthesise?
no
what are fungi bodies normally organised into?
a mycelium made from thread like structures called hyphae which contain many nuclei
are fungi multicellular?
some are, some aren’t
what are the cell walls of fungi made of?
chitin
how do fungi feed?
using saprotrophic nutrition
what is saprotrophic nutrition?
digestive enzymes are secreted outside of the cell onto the food, which is then broken down into small soluble molecules and absorbed by the decomposer
are protoctists multicellular?
not usually
what are some examples of protoctists?
animal-like: amoeba
plant-like: chlorella, plasmodium
are bacteria multicellular?
no
are bacteria eukaryotic?
no, they’re prokaryotic
what do bacteria have instead of a nucleus?
a circular chromosome of DNA
can bacteria photosynthesise?
some can, but most feed off of dead organsisms
what do bacteria cells contain?
a cell wall, a cell membrane, cytoplasm, plasmids, and a circular chromosome of DNA
what might be pathogens?
fungi, bacteria, protoctists, viruses
are viruses living?
no
how big are viruses?
smaller than bacteria
are viruses parasitic?
yes
what is the structure of a virus?
a protein coat and ne type of nucleic acid (either RNA or DNA)
what are some examples of viruses?
tobacco mosaic virus (causes discolouring of tobacco pant leaves by preventing formation of chloroplasts)
influenza virus (causes the flu)
HIV (causes AIDS)
what kind of organisms do viruses infect?
every type of living organisms
what is a pathogen?
a pathogen are microorganisms which cause infectious disease. they harm the host by releasing toxins or damaging cells
all viruses are pathogens, fungi, bacteria and protoctists can be pathogenic (but not all of them are)
what is the function of the nucleus?
controls the activity of the cell (by making proteins)
contains the chromosomes - strands of DNA which carry the genes
what is the function of the cytoplasm?
it is where reactions occur
what is the function of the cell membrane?
controls what substances go in and out of the cell (it is semi-permeable)
what is the function of the cell wall?
keeps the cell in a fixed shape and prevents the cell bursting
what is the function of the mitochondria?
site of respiration, produces ATP
what is the role of the chloroplasts?
light energy absorption, site of photosynthesis, produces chemical molecules for the plant/cell
what is the function of the ribosomes?
site of protein synthesis (from amino acids)
what is the function of the vacuole?
stores dissolved sugars, mineral ions, and other substances
what are the similarities and differences of plant and animal cells?
both have: nucleus, mitochondria, cell membrane, cytoplasm, ribosomes
just plant: cell wall (cellulose), chloroplasts, vacuole
just animal: n/a
what are the chemical elements present in carbohydrates?
CHO
what are the chemical elements present in proteins?
CHON
what are the chemical elements present in lipids?
CHO
what is the smallest unit of carbohydrates?
glucose (monosaccharide)
what does glucose make up?
starch (polysaccharide)
what is the smallest unit of proteins?
amino acids
what is the smallest unit of lipids?
fatty acids and glycerol
how do you test for glucose?
- place a small sample (approx. 2cm^3) of food in a test tube
- then add 1cm^3 of Benedict’s solution, or enough for it to appear blue
- then heat in an 85 degree celcius water bath for 5 minutes
- if the mixture turns from blue to green/yellow/orange/brick red then sugar is present
how do you test for starch?
- take a small sample of food and place it in a well on a spotting tile
- add 10 drops of iodine solution/a roughly equal amount of iodine to food
- if starch is present, the iodine changes from orange to black/blue
how do you test for proteins?
- place a small food sample in a test tube
- add a roughly equal amount of Biuret solution or enough for the pale blue colour to be seen
- if the mixture turns from blue to mauve/purple, proteins are present
how do you test for lipids (fats)?
- place a small food sample in a test tube
- add roughly equal amount of ethanol and mix well
- add roughly equal amount of water (1:1:1) and mix well again
- if the mixture turns milky, fat is present
how do enzymes work as biological catalysts in metabolic reactions?
they lower the activation energy needed for the reaction to occur. they speed up reactions, by the lock and key theory; the enzyme’s active site will fit the substrate perfectly and make the reaction happen
how does temperature change effect enzymes?
as temperature increases, the enzymes and the substrate get more kinetic energy, so more enzyme-substrate complexes are formed as thee are more collisions. as the temperature increases past the optimum temperature, enzymes denature, as they have too much kinetic energy so the enzyme’s active site denatures, so the substrate can no longer fit, so there are less/no enzyme substrates formed
how would you test to see how temperature effects enzyme activity?
- place single drops of iodine solution in rows on the spotting tiles
- label a test tube with the temperature to be tested (eg. 10 degrees celcius)
- use cold water from the tap and hot water from the kettle to prepare a water bath at that temperature, and keep it at that temperature for the test using a thermometer
- use a syringe to place 2cm^3 of amylase into the test tube, then place it in the water bath for 5 minutes
- use another syringe to add 2cm^3of starch solution to the amylase solution (leaving the test tube in the water bath) start the stop watch and mix using the pipette
- after 30 seconds, use the pipette to squirt one drop of iodine solution into the first drop of iodine, the squirt the rest of the pipette back in the test tube. the iodine solution should turn blue/black
- after another 30 seconds, drop another drop of the solution into the next iodine drop
- repeat step 7 until the iodine stays orange
- count how many iodine drops you used, each equals 30 seconds of reaction time
- repeat 1-9 for each temperature (eg 20, 30, 40, 50, 60)
- repeat each temperature 3 times and work out a mean
what is the definition of diffusion?
the random movement of particles from an area of high concentration to an area of low concentration
what is the definition of osmosis?
the net diffusion of free water molecules from an area of high water potential to an area of low water potential across a partially permeable membrane
what is the definition of active transport?
the movement of molecules from an area of low concentration to an area of high concentration using ATP
what factors effect the rate of diffusion and osmosis?
temperature, surface area to volume ratio, distance, concentration gradient
how does temperature affect the rate of diffusion/osmosis?
at higher temperatures, molecules have more kinetic energy, so they move faster, so diffusion (/osmosis) happens faster
how does distance affect the rate of diffusion/osmosis?
shorter distance means the molecules can get there quicker, so the diffusion is faster with smaller distances
how does the concentration gradient affect diffusion/osmosis?
if there is a very big difference in concentration, molecules will diffuse quickly, if the difference is small, they diffuse slower
how does surface area to volume ratio affect diffusion/osmosis?
surface area increases the rate of diffusion because there are more opportunities for the molecules to move in. if you have many small things instead of one big thing, the sa:v increases so the rate increases too
write the method to investigate osmosis in a living organism?
- use a cork borer to cut 5 cylinders out of a potato
- use a knife to cut the cylinders to all the same length (about 3cm)
- accurately measure the potatoes then accurately weigh them
- measure out 75ml of 1.0M salt solution and put it into a boiling tube and label it
- repeat step 4 for 0.0M, 0.25M, 0.50M, 0.75M salt solutions
- draw out a table of results
- add one potato cylinder to each boiling tube and make sure that you know the measurement of each potato
- leave each potato in the boiling tube for at least 15 minutes
- take the potatoes out of the boiling tube and pat dry with a paper towel
- measure the mass of each potato cylinder and record it in the table and calculate the percentage change for each potato cylinder
- plot a graph of change in mass /g (y) against the concentration of salt solution /M, then find the x-intercept to find the isotonic point of the potato
photosynthesis converts what into what?
it converts light energy to chemical energy
what is the word equation for photosynthesis?
water + carbon dioxide -light energy-> oxygen + glucose
what is the balanced chemical equation for photosynthesis?
6H(2)O + 6CO(2) –> 6O(2) + C(6)H(12)O(6)
what factors affect the rate of photosynthesis?
- carbon dioxide concentration
- light intensity
- temperature
how does varying carbon dioxide concentration affect photosynthesis?
a higher concentration of carbon dioxide increases the rate of photosynthesis because there are more molecules for the enzymes to collide with
at a certain point, increasing the concentration doesn’t change anything, as it is no longer the limiting factor
how does varying light intensity affect the rate of photosynthesis?
increasing the light intensity increases the rate of photosynthesis because there is more energy for the reaction to occur
at a certain point increasing the light intensity doesn’t change anything because something else has become the limiting factor
how does varying the temperature affect the rate of photosynthesis?
increasing temperature increases the rate of reaction as the enzymes and substrates have more kinetic energy so they collide more often so there are more successful enzyme-substrate complexes formed. this is until the temperature increases past the optimum, where the rate slows down as the enzymes have too much kinetic energy and denature as their active site changes shape so the substrate no longer fits, so there are less/no enzyme-substrate complexes form, so the rate of reaction does not increase
describe the structure of a leaf and explain how it is adapted for photosynthesis
- the waxy cuticle prevents water loss via evaporation and osmosis through the leaf
- the transparent upper epidermis allows the light to reach the palisade mesophyll layer
- the palisade mesophyll layer cells are thin, long, and tightly packed together and have lots of chloroplasts to maximise the amount of light energy absorbed for photosynthesis
- the spongy mesophyll layer has air spaces for carbon dioxide diffusion
- the xylem transports the water into the leaf so there is a short diffusion distance
- the phloem allows the sugars produced in photosynthesis to be transported to other respiring cells
- the stomata and guard cells control the amount of water transpiration and the amount of carbon dioxide diffusion into the cell depending on the amount of light
what do plants use magnesium ions for?
they are needed to make chloroplasts
what do plants use nitrate ions for?
it is needed to make amino acids, for cell growth
what do plants need phosphate ions for?
it is needed to make DNA
describe the method to investigate how light intensity affects photosynthesis
- place the beaker of pondweed 10cm away from the light source
- count the number of bubbles produced in one minute (using a stopwatch
- repeat twice more and record the mean
- repeat 1-3 for 4 more distances, eg. 15cm, 20cm, 25cm, 30cm
- record the results in a table
describe the method to investigate wether carbon dioxide is needed for photosynthesis
- de-starch the plant by putting it in a dark cupboard for 24 hours
- put a conical flask containing potassium hydroxide around one leaf, this will absorb the carbon dioxide in the air
- put an empty conical flask around another leaf as a control test
- place the plant in a bright place
- test both leaves for starch using iodine solution (drop it in boiling water, place it in hot ethanol for 5-10mins, spread on a white tile and drop iodine solution over it)