Organisms and life processes Flashcards
what is mitochondria
site of aerobic respiration
what are the 2 microscopes
light microscopes - very mobile, used in schools, (relatively) low magnification - so many organelles/sub-cellular structures can’t be seen using light microscopes
electron microscopes - much much better resolution and higher magnification
how does temperature affect the rate of enzyme-catalysed reaction?
independent variable = the thing that YOU are changing
dependent variable = the thing that you are MEASURING
control variable = things you keep the same
Independent variable goes on the x axis
dependent variable goes on the y axis
As you go from … to … on the x-axis, something happens in the y-axis
As you go from 10-40degrees celsius, the rate of enzyme-catalysed reaction steadily increases. This is because the particles have more kinetic energy, and so there are more successful enzyme-substrate collisions. From 40-60 degrees, there is a rapid decrease in the rate of enzyme-catalysed reaction, as past this optimal temperature (40), the enzymes start to denature. So, the active site loses its shape, and so is no longer complementary to the substrates, so they can no longer bind, so the rate of enzyme-catalysed decreases.
(example)
ph affect on enzymes
as you go from Ph 1 to Ph 3 the rate of enzyme catalysed reactions steadily increases with reactions being best catalysed at its optimum Ph 3, this is because pepsinogen is present in stomach acid which has a realtive
low ph so pepsinogen will work best at Ph 3, as you go from Ph 3 to Ph 7 the enzyme activity steadily decreases with more becoming fully destructurealised at ph 7
what is this the difference between the graphs for ph and temperature
the graph is more parabolic on ph than temperature which has a steady slow increase towards optimum temp and then rapidly decreasing to denatured, with ph the slope is same on both sides
what group do bacteria fall into eu or prokaryotic?
STRICTLY PRO
what are alveoli adapted with
alveoli are adapted with:
alveolar wall and caplillary wall are each one cell thick so there is a very short diffusion distance
alveoli have a rich blood supply which maintains a steep concentration gradient
alveoli have a very large SA:V
factors that affect rate of diffusion
Factors that affect the rate of diffusion
temperature
SA:V
diffusion distance
steepness of concentration gradient
what are examples of transport
Examples of transport:
oxygen from lungs to body
CO2 from body to lungs
Nutrients (glucose) from gut to body
Urea from liver to kidneys
why do multicellular organisms need a transport systems and uni dont
Unicellular organisms do not require a transport system as they have an incredibly large surface area to volume ratio –> this means they can just diffuse things in and out
HOWEVER, with multicellular organisms, the larger the organism, the smaller the SA:V ratio
SO, they cannot simply diffuse things in - they need complex transport systems
what is diffusion
Diffusion = the passive, NET movement of particles down a concentration gradient
what is osmosis
Osmosis = the passive NET movement of WATER particles from a dilute to concentrated solution (from a high concentration OF WATER particles, to a low concentration OF WATER particles)
what is active transport
Active transport = the movement of particles against the concentration gradient, using energy
whats the purpose of lignen spirals
to keep the the cells not collapsing
what is the xylem and how is it formed
Xylem is a tissue that transports water and mineral ions
How does xylem form:
cells line up end to end and then die
the cell wall between the cells dissolve leaving a tube
lignin spirals form in the cell wall, for support
Lignin lets the xylem carry water up the plant without collapsing, and is impermeable to water
what are sieve plates
they are holes in the cells wall inbetween each other, not on the outside
companion cells
provides phloem with energy for active transport and controls the phloem cells since they have no nucleus
do phloems cells have a nucleus
no
what happens to the xylem and phloem as they get older
As plants get older, the vascular tissue grows to form complete rings, with the xylem as a woody central core and phloem as a living layer on the outside.
this is why there are rings on wood when you cut them
what would the vasuclar bundle look like in a cross section
if you cut a stem you would see vascular bundles on the perimeter just like numbers on a clock
desrcibe chloroplasts and respiration in plants
The chlorophyll in cells in the leaf absorb light energy to be used in photosynthesis.
respiration - glucose + oxygen –> carbon dioxide + water
photosynthesis - carbon dioxide + water –> glucose + oxygen
desribe everything about stomata, how they work, why they arent on the upper side of the leave, guard cells, how they work
Stomata = little holes on the underside of the leaf controlled by guard cells
Why are stomata found on the bottom of leaves and not on the top:
if they were on the upper side, the direct sunlight would produce a high rate of evaporation.
also, the air on the underside of leaves has less air movements
SO guard cells being at the bottom of leaves leads to less water loss
How do guard cells work to open and close the stomata:
In the light, guard cells are the only cells in the lower epidermis that have choroplasts –> they absorb light energy and use it to build up solutes in their vacuole. “water follows salt”. So, water moves into the cells, making them turgid. they swell up and bend outwards, opening the stomata.
Why is it good that stomata close in the dark:
To prevent water loss - there is no need for them to open as there is no need for carbox dioxide as photosynthesis cannot happen when it’s dark
Temperature ( the particles have more energy so they dffuse faster at higher temperatures, and the water evaporates at a higher rate from mesophyll cells. This means that higher temperature leads to higher rate of transpiration.
Light intensity = increased light intensity means more stomata will be open as more CO2 will be needed as more photosynthesis will be occurring. This means that higher LI leads to higher rate of transpiration.
Humidity (it is easier for water to evaporate into dryer air than more saturated air because of the difference in concentration gradient. This means lower humidity leads to higher rate of transpiration.
Wind speed ( faster wind speed causes more transpiration because the wind can easily remove the water from the surroundings of the leave, maintaining a steep concentration gradient. this means high wind speed/more air movement leads to higher rate of transpiration.
what does plasmolysed means
the point where even more water is osmosed out of the cell and the cell memebrane stretches away from the cell wall
