2. STRUCTURE & FUNCTIONS IN LIVING ORGANISMS Flashcards
2.2 cells are separated from their surrounding environment by
a cell membrane
2.2 within the cell membrane is the
cytoplasm
2.2 eukaryotic cells have … contained within their cytoplasm
organelles
2.2 organelles are
where specific processes take place within the cell
2.2 what is in the cytoplasm of a eukaryotic cell
nucleus, mitochondria & ribosomes
2.2 plant cells contain the following additional structures
cell wall, chloroplasts & a vacuole
2.3 function of the nucleus
contains genetic material in chromosomes
controls cell division
2.3 function of the cytoplasm
supports cell structure
site of many chemical reactions
contains water and many solutes
jelly-like substance
2.3 function of the cell membrane
holds the cell together
controls substances entering and leaving the cell
2.3 function of the cell wall
gives the cell extra support and defines its shape
2.3 function of the mitochondria
site of aerobic respiration providing energy for the cell
2.3 function of the chloroplasts
site of photosynthesis - provides food for plants
chlorophyll pigment absorbs light energy
2.3 function of the ribosomes
the site of protein synthesis
2.3 function of the vacuole
contains cell sap
used for storage
helps support the shape of the cell
2.4 how many structures does a plant cell have
8
2.4 how many structures does an animal cell have
5
2.4 in addition to the structures an animal cell has, a plant cell also has
chloroplasts, a (cellulose) cell wall and a vacuole
2.4 what does an animal cell have
a nucleus, cell membrane, mitochondria, ribosomes and a cytoplasm
2.4 what does a plant cell have
a nucleus, cell membrane, mitochondria, ribosomes, cytoplasm, chloroplasts, cell wall and a vacuole
2.7 the chemical elements present in carbohydrates
carbon, hydrogen and oxygen
(C,H,O)
2.7 the chemical elements present in proteins
carbon, hydrogen, oxygen and nitrogen
(C,H,O,N)
2.7 the chemical elements present in lipids (fats&oils)
carbon, hydrogen and oxygen
(C,H,O)
2.8 starch and glycogen is from
simple sugars
2.8 protein is from
amino acids
2.8 lipids are from
fatty acids and glycerol
2.8 a monosaccharide is a …
simple sugar like glucose
2.8 a disaccharide is made when
two monosaccharides join together e.g. maltose = glucose & glucose
sucrose = glucose & fructose
2.8 a polysaccharide is formed when
lots of monosaccharides join together
2.8 polysaccharides starch, glycogen or cellulose are all formed when
lots of glucose molecules join together
2.8 most fats (lipids) in the body are made up of
triglycerides
2.8 lipids basic unit is
one glycerol molecule chemically bonded to three fatty acid chains
2.8 proteins are formed from
long chains of amino acids
2.8 when amino acids are joined together
a protein is formed
2.9 what is the test for starch?
iodine solution
2.9 explain the test for starch
- place food sample on a spotting tile
- add a few drops of iodine solution to the sample
- blue - black colour indicates starch
2.9 what is the test for glucose / reducing sugars?
benedicts solution
2.9 explain the test for glucose / reducing sugars?
- place food sample in a boiling tube
- add benedict’s solution to the sample of food in solution
- place in a water bath at 80*c for 5 minutes
- a change from blue to brick red if present
(if green, yellow or orange means less sugar present)
2.9 what is the test for protein?
biuret test
2.9 explain the test for protein
- place food sample in a boiling tube
- add enough biuret solution for colour to be pale blue
- if protein is present colour will change to mauve / purple
2.9 what is the test for lipids?
emulsion test
2.9 explain the test for lipids?
- place food sample in a test tube
- add small amount of ethanol and shake to dissolve any lipid in the alcohol.
- add equal volume of water
- cloudy white colour (emulsion will form) indication presence of lipid
2.9 benedicts solution is used to test for
reducing sugars (glucose)
2.9 benedicts solution colour change
blue to brick red
2.9 how do I remember benedicts solution
christmas sugar
2.9 iodine is used to test for
starch
2.9 iodine solution colour change
orange to blue-black
2.9 how do I remember iodine
bumblebee
2.9 biuret is used to test for
protein
2.9 biuret solution colour change
(light)blue to pale purple
2.9 how do I remember biuret
snowflakes
(et) proTEin biurET
2.9 emulsion is used to test for
lipids
2.9 emulsion colour change
colourless to a cloudy white emulsion
2.9 how do I remember emulsion
snowing
2.10 enzymes are biological
catalysts
2.10 a catalyst is a ……..
chemical which increases the rate of a reaction without being used up itself in the reaction
2.10 the theory for understanding how enzymes work is the
lock and key theory
2.10 what is the lock and key theory
the substrate and enzyme collide,
the substrate binds to the active site of the enzyme,
(the reaction occurs by an alternative pathway with a lower activation energy)
once the reaction occurs, the products don’t fit - so they are released,
the enzyme is free to catalyse the next reaction
2.10 the active site has a particular shape which is … to the shape of the substrates
complementary
2.10 because the shape of the active site is complementary to that of the substrates, this means
each enzyme can only catalyse one reaction
2.11 as temperature increases the enzyme & substrate have more
kinetic energy
so they move faster and there are more successful collisions
2.11 high temperatures and changes of pH cause the shape
to change
2.11 when the shape changes we say this is
the protein being denatured
2.11 when the active site changes shape it is no longer
complementary to the substrate
2.12 practical for investigating effect of temperature on enzymes
mix
10cm3 of 10% starch suspension
+ 5cm3 of 5% amylase
in a boiling tube
heat in water bath
every minute take 1 drop of the mix
add to 1 drop of iodine solution
in spotting tile
when digestion is complete
iodine solution will stay orange
(no starch)
repeat using water baths at different temperatures
2.15 definition of diffusion
the random movement of particles from an area of higher concentration to an area of lower concentration
2.15 definition of osmosis
the net diffusion of free water molecules from an area of high water concentration to an area of low water concentration across a partially permeable membrane
2.15 osmosis in cell:
what is: solution outside cell has same water potential as inside cell - no net movement
isotonic solution
(animal = normal)
(plant = flaccid)
2.15 osmosis in cell:
what is: solution outside cell has higher water potential then inside cell - net movement of free water molecules into cell
hypotonic solution
(animal = lysed)
(plant = turgid)
2.15 osmosis in cell:
what is: solution outside cell has lower water potential then inside cell - net movement of free water molecules out of cell
hypertonic solution
(animal = shrivelled)
(plant = plasmolysed)
2.15 definition of active transport
movement of molecules from an area of low concentration to an area of high concentration using ATP
2.16 the four main factors that affect the rate of movement
surface area to volume ratio, distance, temperature and concentration gradient
2.16 why is a larger surface area a good thing
it quickens the rate at which substances can move across its surface
2.16 example of large surface area
highly folded surface of the small intestine increases its surface area
2.16 why is a shorter distance a good thing
the smaller the distance molecules have to travel, the faster the transport will occur
2.16 example of short diffusion distance
alveoli walls are one cell thick - rate of diffusion across them is as fast as possible
2.16 why is higher temperature a good thing
the higher the temperature, the faster molecules move as they have more energy
2.16 how is higher temp a good thing
because there are more collisions against the cell membrane and therefore a faster rate of movement across them
2.16 why is a greater difference in a concentration gradient a good thing
the greater the difference in concentration on either side of the membrane, the faster movement across it will occur
2.16 how is a greater difference in a concentration gradient a good thing
because the on the side with the higher concentration, more random collisions against the membrane will occur
2.17 practical: investigating diffusion
coloured agar is made from indicators
coloured agar is cut into required dimensions
calculate the surface area, SA:V R and volume and record it
cubes placed in boiling tubes of different solutions (same volume of it)
^^^ e.g. dilute hydrochloric acid
measurements taken of time for cube to completely change colour of indicator
can draw a graph of rate of diffusion (rate of colour change) changes with surface area : volume ratio of agar cubes
2.17 practical: investigating osmosis
prepare a range of sucrose (sugar) solutions ranging from 0 Mol/dm3 (distilled water) to 1 mol/dm3
set up 6 labelled test tubes with 10cm3 of each of the sucrose solutions
using the knife, cork borer and ruler, cut 6 equally-sized cylinders of potato
blot each one with a paper towel and weigh on the balance
put 1 piece into each concentration of sucrose solution
after 4 hours, remove them, blot with paper towels and reweigh them
2.18 process of photosynthesis
energy from sunlight is absorbed by chlorophyll, a green pigment found inside chloroplasts
green plants use this energy to make the carbohydrate glucose from the raw materials carbon dioxide and water
at the same time, oxygen is made and released as a waste product
2.19 word and balanced chemical equations for photosynthesis
carbon dioxide + water -> glucose + oxygen
6CO2 + 6H2O -> C6H12O6 + 6O2
2.20 how does varying temperature affect the rate of photosynthesis
it affects how much kinetic energy the particles have so affects the speed at which carbon dioxide and water move
more successful collisions
(too high temp can denature enzymes that control the process of photosynthesis)
2.20 how does varying light intensity affect the rate of photosynthesis
the intensity of the light available to the plant will affect the amount of energy that it has to carry out photosynthesis
the more light a plant receives, the faster the rate of photosynthesis
2.20 how does varying carbon dioxide concentration affect the rate of photosynthesis
carbon dioxide is one of the raw materials required for photosynthesis
this means the more carbon dioxide that is present, the faster the reaction can occur
2.21 structure of waxy cuticle
protective layer on top of the leaf prevents water from evaporating
2.21 structure of upper epidermis
thin and transparent to allow light to enter palisade mesophyll layer underneath
2.21 structure of palisade mesophyll
column shaped cells tightly packed with chloroplasts to absorb more light maximising photosynthesis
2.21 structure of spongy mesophyll
internal air spaces which increase surface area to volume ratio for the diffusion of gases (mainly carbon dioxide)
2.21 structure of lower epidermis
contains guard cells and stomata
2.21 structure of guard cell
absorbs and loses water to open and close stomata to allow
carbon dioxide to diffuse in
oxygen to diffuse out
2.21 structure of stomata
where gas exchange takes place
opens during day closes during night
evaporation of water takes place here
found in much greater concentration on underside of leaf to reduce water loss (in most plants)
2.21 structure of vascular bundle
contains xylem and phloem to transport substances to and from the leaf
2.21 structure of xylem
transports water into leaf for mesophyll cells to use in photosynthesis and for transpiration from stomata
2.21 structure of phloem
transports sucrose and amino acids around the plant
2.21 what are all the 10 leaf structures
waxy cuticle, upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis, guard cell, stomata, vascular bundle, xylem and phloem
2.21 adaptation of large surface area (leaf)
increases surface area for the diffusion of carbon dioxide and absorption of light for photosynthesis
2.21 adaptation of being thin
allows carbon dioxide to diffuse to palisade mesophyll cells quickly
2.21 adaptation of chlorophyll
absorbs light energy so that photosynthesis can take place
2.21 adaptation of network of veins
allows the transport of water to the cells of the leaf and carbohydrates from the leaf for photosynthesis
(water for photosynthesis)
(carbohydrates - product of photosynthesis)
2.21 adaptation of stomata
allows carbon dioxide to diffuse into the leaf and oxygen to diffuse out
2.21 adaptation of epidermis being thin and transparent
allows more light to reach the palisade cells
2.21 adaptation of thin cuticle made of wax
to protect the leaf without blocking sunlight
2.21 adaptation of palisade cell layer at top of leaf
maximises the absorption of light as it will hit chloroplasts in the cells directly
2.21 adaptation of spongy layer
air spaces allow carbon dioxide to diffuse through the leaf increasing surface area
2.21 adaptation of vascular bundles
thick cell walls of the tissue in the bundles help to support the stem and leaf
2.21 specialised leaf for photosynthesis: large surface area and thin
to maximise absorption of sunlight and increases number of stomata so carbon dioxide can diffuse faster