Organisms and life processes

Question 1

what is mitochondria

Answer 1

site of aerobic respiration

Question 2

what are the 2 microscopes

Answer 2

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

Question 3

how does temperature affect the rate of enzyme-catalysed reaction?

Answer 3

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)

Question 4

ph affect on enzymes

Answer 4

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

Question 5

what is this the difference between the graphs for ph and temperature

Answer 5

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

Question 6

what group do bacteria fall into eu or prokaryotic?

Answer 6

STRICTLY PRO

Question 7

what are alveoli adapted with

Answer 7

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

Question 8

factors that affect rate of diffusion

Answer 8

Factors that affect the rate of diffusion
temperature
SA:V
diffusion distance
steepness of concentration gradient

Question 9

what are examples of transport

Answer 9

Examples of transport:
oxygen from lungs to body
CO2 from body to lungs
Nutrients (glucose) from gut to body
Urea from liver to kidneys

Question 10

why do multicellular organisms need a transport systems and uni dont

Answer 10

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

Question 11

what is diffusion

Answer 11

Diffusion = the passive, NET movement of particles down a concentration gradient

Question 12

what is osmosis

Answer 12

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)

Question 13

what is active transport

Answer 13

Active transport = the movement of particles against the concentration gradient, using energy

Question 14

whats the purpose of lignen spirals

Answer 14

to keep the the cells not collapsing

Question 15

what is the xylem and how is it formed

Answer 15

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

Question 16

what are sieve plates

Answer 16

they are holes in the cells wall inbetween each other, not on the outside

Question 17

companion cells

Answer 17

provides phloem with energy for active transport and controls the phloem cells since they have no nucleus

Question 18

do phloems cells have a nucleus

Answer 18

no

Question 19

what happens to the xylem and phloem as they get older

Answer 19

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

Question 20

what would the vasuclar bundle look like in a cross section

Answer 20

if you cut a stem you would see vascular bundles on the perimeter just like numbers on a clock

Question 21

desrcibe chloroplasts and respiration in plants

Answer 21

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

Question 22

desribe everything about stomata, how they work, why they arent on the upper side of the leave, guard cells, how they work

Answer 22

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

Question 23

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.

Question 24

what does plasmolysed means

Answer 24

the point where even more water is osmosed out of the cell and the cell memebrane stretches away from the cell wall

Question 25

what is respiration

Answer 25

Respiration = a chemical reaction in which glucose and oxygen react to produce carbon dioxide and water, which releases energy to be used by the cells

Question 26

what is the word and symbol equation for respiration

Answer 26

glucose + oxygen —-> carbondioxide + water

C6H12O6 + O2 —> 6CO2 + 6H2O

Question 27

what is aerobic respiration and where does it take palce

Answer 27

Aerobic respiration takes place when there is a sufficient amount of oxygen
This takes place in the mitochondria of the cell

Question 28

what is anaerobic and where does it take place

Answer 28

Anaerobic respiration takes place when there is an insufficient amount of oxygen
This takes place in the cytoplasm

Question 29

what is ATP and what is it made out of

Answer 29

ATP is a store of energy (NOT. a definition) - adenosine triphosphate
ATP is made up of (just think about the name) - one adenosine molecule (organic molecule) and three phosphate molecules

Question 30

how does ATP release energy

Answer 30

When ATP is broken down, it loses one phosphate molecule, making it adenosine diphosphate (ADP)
This breakdown from ATP to ADP releases chemical energy

Question 31

how do muscles respire anaerobically

Answer 31

Muscle cells respire anaerobically when they are contracting a lot, and the blood is not flowing fast enough to supply them with a sufficient amount of oxygen
Anaerobic respiration releases a considerably lower amount of energy compared to aerobic respiration

Question 32

what is oxygen debt

Answer 32

oxygen debt is when, atfer the anerobic respiration is finished, the lactic acid must be broken down into energy using oxygen so the oxygen that will be used to for this called oxygen debt

Question 33

what is the word equation for anaerobic respiration

Answer 33

glucose —–> lactic acid + ATP

Question 34

why does lactic acid need to be broken down

Answer 34

Oxygen oxidises lactic acid, breaking it down
lactic acid is toxic - the build up of it leads to muscle fatigue and soreness

Question 35

What are the adaptations of the nerve cell (3)

Answer 35

Nerve cell:
lots of dendrites to make connections to other neerves
Axon carries nerve impulse
Synapses to pass the impulses to another nerve or muscle using a chemical called neurotransmitters

Question 36

what are the adaptations of the smooth muscle cell (4)

Answer 36

Smooth muscle cell:muscles in human digestive system contract to squeeze food through the gut - peristalsis
Contains special proteins which slide over each other to contract
- Many mitochondria for energy release from aerobic respiration to be used in muscle contraction
Can store glycogen - used in cellular respiration

Question 37

what are the adaptations of the sperm cell (3)

Answer 37

Sperm cells:
- genetic information from male parent
- Long tail to swim - needed to get to the egg
- middle section of sperm contains mitochondria - transfers energy to the tail for it to move to swim
Acrosome (front part of the head)- stores digestive enzymes - to break down the outer layers of the egg

Question 38

why is breathing rate high after exercise

Answer 38

During exercise there is a lot of contraction
So, there is a lot of energy required
So, due to insufficient oxygen, muscles anaerobically respire
So, the body goes into oxygen debt as lactic acid is produced
So after exercise, breathing rate is high to supply sufficient oxygen to the muscles to get rid of the lactic acid
it is high to remove CO2