Photosynthesis and Ecology

Question 1

What is the definition of ‘producer’?

Answer 1

An organism that converts light energy to chemical energy for food, i.e. green plants or algæ.

Question 2

What is the definition of ‘consumer’?

Answer 2

An organism that eats other organisms.

Question 3

What is the definition of ‘decomposer’?

Answer 3

An organism that breaks down dead organic matter and waste products to release nutrients, e.g. earthworms, fungi, bacteria, insects.

Question 4

What is photosynthesis?

Answer 4

The making of glucose (i.e. food) from CO2 and water by green plants using light energy, which is absorbed by chlorophyll.

Question 5

How does photosynthesis occur?

Answer 5

CO2 diffuses through the stomata in the leaf, water and nutrients travel up the xylem and sunlight is absorbed through chlorophyll.
Approximately 1% of the absorbed sunlight is used in photosynthesis.

Question 6

What is chlorophyll?

Answer 6

It is a green chemical pigment stored inside chloroplasts that allows for photosynthesis. It absorbs blue and red light but reflects green.

Question 7

What is the word equation for photosynthesis?

Answer 7

Carbon dioxide + Water = Glucose + Oxygen (+ chemical energy).
It is a photochemical reaction and can only occur with light.

Question 8

How will a destarched leaf prove that light is needed for photosynthesis?

Answer 8

Place a leaf in the dark while in tinfoil for 24 hours. It will destarch, but as soon as it is taken out it will recommence photosynthesis instantly. Firstly, dip it in boiling water (kills leaf + stops all processes + breaks cells open).
Secondly, place it in a test tube with ethanol (will remove chlorophyll to definitely stop photosynthesis occurring (the leaf may be dead but the ingredients are still inside)) before placing said test tube in water bath. ETHANOL IS FLAMMABLE — MAKE SURE BUNSEN BURNER IS OFF.
Thirdly, dip leaf back into boiling water (it will soften leaf as ethanol stiffens it).
Finally, place the leaf on a tile and test for starch (the chains of glucose produced by photosynthesis will become polysaccharides) w/ iodine. Iodine is an irritant + will stain.
Orange-brown: no starch.
Blue-black: starch is present.

Question 9

Can all parts of a plant photosynthesise?

Answer 9

No — only the green parts, which is why some plants that live in areas with little light are nearly completely green.

Question 10

How do plants survive at night without light?

Answer 10

They aerobically respire — O2 + glucose (C6H12O6) —> CO2 + H2O (+ energy).

Question 11

Why is photosynthesis important for all organisms?

Answer 11

Oxygen is a waste product of photosynthesis, but it is necessary for breathing. It is also how the Sun passes energy along to all organisms.

Question 12

What is a habitat?

Answer 12

The place where an organism lives.

Question 13

What is a community?

Answer 13

A group of organisms in a habitat.

Question 14

What is a population?

Answer 14

The amount of a particular species that inhabit a habitat.

Question 15

What causes the environment in a habitat?

Answer 15

Physical environmental factors.

Rain, light, temp., water availability, etc.

Question 16

What is distribution?

Answer 16

A description of where a particular organism’s species can be found.

Question 17

What is the environment like in a desert?

Answer 17

Hot during day, cold during night.
High average temperatures that can reach up to 50°C. 
Little precip. + water.
Infertile sierozem soil.
Windy.
Little vegetation.
Much sand.
Plenty of light.

Question 18

What is the environment like in the Arctic?

Answer 18

Very cold/icy but little-to-no running water.

Either much light or darkness, depending on the season.

Question 19

What is the environment like underwater?

Answer 19

Majority of oxygen produced by phytoplankton near surface.
Light decreases further down.
Temp. depends on depth and location.

Question 20

What is the environment like in woodland?

Answer 20

Temperate/cool/mild.
The more light, the more water taken for photosynthesis, but water avail. varies.
Temperature depends on depth/location.

Question 21

What is a micro-habitat?

Answer 21

A small habitat, e.g. one under a log.

Question 22

What is the point of adaptations?

Answer 22

They enable better survival (survival of the fittest) as they make the organism suited to where it lives.

Question 23

Name an organism that lives in the desert and list some of its adaptations.

Answer 23

Camel
Camels have long eyelashes — sometimes 2/3 sets — sandstorms.
Wide hooves to prevent sinking.
Hump(s) can store fat + convert it to energy/water.
Fur can be camouflage.

Question 24

How are some plants adapted to photosynthesis?

Answer 24

All green e.g. cactus.
Air-filled bladders to float for light e.g. water lily.
Long stems to reach light e.g. water lily.
Large, flat leaves to maximise light absorption as greater surface area e.g. buttercup, water lily.

Question 25

How are birds adapted to flight? hunting? mating?

Answer 25

Flight: wings/tail as a stabiliser/hollow wishbone.
Hunting: talons.
Mating: different colours for female/male, song.

Question 26

Name an organism that lives underwater and list some of its adaptations.

Answer 26

Fish (e.g. salmon, stickleback, trout, etc.)
Streamlined/possess fins to move through water.
Gills to breathe.

Question 27

Name an organism that lives in the savannah and list some of its adaptations.

Answer 27

Lion
Size and colour of mane determine strength, agility and fitness.
Eyes set in front of head to track/hunt prey more easily — no need to constantly turn head.
Heavily muscled forelimbs/shoulders — rapid acceleration/strength/vice-like grip.
Long, retractable claws to grip/slice prey simultaneously.
Rough tongue — removes meat from bones (and COMB)

Question 28

Name an organism that lives in the Arctic and list some of its adaptations.

Answer 28

Nostrils — can close when swimming + can close to stop cold air getting in.
White fur — camouflage when hunting.
Thick fur — to keep warm.
Non-absorbent fur — to remain near-dry when swimming — acts as a wetsuit (when out, they can shake and are almost instantly dry).
Large feet — don’t sink + wide surface area helps with swimming.
Black skin — can absorb light + heat.

Question 29

If all habitats were the same, what would happen to adaptations?

Answer 29

Adaptations would be mostly useless and animals would have fairly uniform ones, as only certain ones would be necessary regardless of location. Some species with different/wrong adaptations would go extinct.

Question 30

What is an environmental change? when do they occur?

Answer 30

A regular change in an organism’s behaviour. They can occur daily, e.g. nocturnality, or seasonally, e.g. losing leaves.

Question 31

What is a very common trigger for environmental changes?

Answer 31

Temperature:
More clothes
Longer fur
Dropping leaves
Hibernation
Change in coat colour (indirectly linked for Arctic foxes — triggered by melting snow)
Migration

Question 32

What is the first organism in a food chain called? second? third? fourth? last?

Answer 32

Primary producer.
Primary consumer 
Secondary consumer.
Tertiary consumer.
Top carnivore.
Most food chains have four — the tertiary consumer is often the top carnivore.

Question 33

Why are there usually no more than four organisms in a food chain?

Answer 33

Energy is lost up the food chain as it is used and wasted by the organisms.

Question 34

What is the definition of carnivore? herbivore? omnivore?

Answer 34

An organism that only eats animals.
An organism that only eats plants.
An organism that eats both.

Question 35

What is a food chain?

Answer 35

A chain that shows the link betwixt predator and prey.

Question 36

What is a food web? why are they often regarded as better than food chains?

Answer 36

Food webs are many connected food chains that shows how an ecosystem feeds. They are often seen as better because they are more naturalistic — few organisms only consumer one kind of organism.

Question 37

Are all the organisms in a food web linked? If one went extinct, would they all be affected or only some?

Answer 37

Yes. They would all be affected. The organisms in a food web exist in a delicate balance. If this is altered, it will have a ripple effect on all the organisms — some will be badly affected, some not so much, but all will be changed in some way.

Question 38

What happens to energy as it travels up the food chain? why does this happen?

Answer 38

It is lost and wasted. Organisms use it for the seven life processes and other things such as insulation. Therefore, less energy is available further up and the organisms up the chain will have to eat more than one kind of thing.

Question 39

What is a pyramid of biomass?

Answer 39

A pyramid that shows the total mass at each trophic level, e.g.
                   hawk
                  r obi n
                ladybirds
              a  p  h  i  d  s
            p e a p l a n t s

Question 40

What is a pyramid of numbers?

Answer 40

A pyramid that shows the number of organisms at each trophic level, but does not account for size, e.g.
                  top carnivore
         secondary consumer 
       p r i m ary cons u m e r 
      p r i m a r y  p r o d u c e r

Question 41

What is an inverted pyramid?

Answer 41

A pyramid that does not fit the usual conventions and usually looks ‘upside down’. They are often pyramids of numbers, e.g.
                  hawk 
                 r obi n
              l a dybir d s
             a  p  h  i  d  s
                   tree

Question 42

Is all of the biomass passed up a food chain?

Answer 42

No.
Energy is lost up the food chain — energy was part of biomass.
Not all of the organism may be eaten e.g. oak tree.
The diet of the consumer may change during its life cycle rendering it unable to eat the organism any more (?!?).

Question 43

What are the different levels of producers and consumer known as?

Answer 43

Trophic levels.

Question 44

Name an organism that lives underground and list some of its adaptations.

Answer 44

Moles.
Eyes that adjust to the darkness.
Some have very, very sensitive snouts.