Ecology Flashcards
How should the student decide where to place the quadrat?
Give the reason for your answer
(grid and) coordinates
to achieve randomness
Using the mean from this investigation to calculate the number of daisy
plants on the lawn may not be accurate.
Give two reasons why
too few quadrats or quadrat too small
allow sample size too small
sample may not be representative of the lawn
The horn of the Siberian rhinoceros is estimated to have been 150 cm long.
Suggest one advantage of this adaptation to the Siberian rhinoceros.
- fighting / competing for mates / food / territory
- to kill predators / prey
Give one reason why only the bones of the body of the Siberian
rhinoceros became fossils.
(bones or hard tissues) did not decay
Suggest how scientists can estimate when the Siberian rhinoceros was
alive.
- compare to other fossils of known age
allow compare with the fossil record - by the age of the rocks (where fossil was found)
Suggest two factors that may have caused the extinction of the Siberian
rhinoceros.
- drought
- ice age / global warming
- volcanic activity
allow earthquakes / tsunami - asteroid / meteor collision
- (new) predators
allow hunters / poachers / eaten - (new) disease
allow named pathogen - competition for food
allow lack of food - competition for mates
allow isolation or lack of mates - lack of habitat or habitat change
The jerboa is adapted for survival in the desert.
The jerboa spends the daytime in its underground burrow.
The jerboa only leaves its burrow to look for food during the night.
(d) Describe how these adaptations help the jerboa to survive in the desert.
- cooler underground / at night
or
the jerboa can keep cool - loses less water
or
sweats less - less likely to be seen (by predators / prey)
Explain how temperature tolerance can help the dromedary to survive in
the desert.
less sweating so less water loss
(as) no / little water available in deser
The student wanted to get a more valid estimate of the percentage cover of
buttercup plants in the field.
Suggest two improvements to the method to make the results more valid.
- place (many) more quadrats
allow repeat
allow combine results with results of
other students - divide quadrats into more / smaller squares
- estimate actual percentage cover in quadrat (instead of
counting squares) - only count squares with at least 50% cove
Give three environmental factors that would affect the growth of buttercup
plants in a field.
- light
- water
allow rain / moisture - minerals / ions / salts
allow named example such as nitrate /
phosphate
allow fertiliser - pH
- temperature
- herbivores
allow named example - trampling / cultivation
- describe how microorganisms in the layers of soil help to recycle chemicals in the
dead plants - how the chemicals are used again by living plants.
- digestion or large molecules to small molecules
- enzymes or named example
- respiration
- production of carbon dioxide
- release of mineral ions or named example such as nitrate /
phosphate / magnesium
in plants - carbon dioxide (from air) taken in by leaves
- by diffusion
- via stomata
- carbon dioxide used in photosynthesis
- making glucose / sugar / starch / cellulose or making other correctly
named example - (named) ions taken in by roots
- by active transport
- nitrate ions for making amino acids / proteins / DNA / chlorophyll
- phosphate for making DNA
Name two types of microorganism that cause decay.
bacteria
fungi
Name the product that causes the pH to decrease
fatty acid(s)
Which type of milk stays fresh the longest at 10 °C?
almond (milk)
The time taken for cows’ milk to reach pH 5 at 10 °C is less than the time
taken for cows’ milk to reach pH 5 at 5 °C Suggest one reason why
- bacteria / microbes / microorganisms / fungi dividing faster
(when warmer)
allow converse if clearly describing 5 °C
allow number of bacteria / microbes /
microorganisms / fungi increasing
(when warmer)
allow more bacteria microbes /
microorganisms / fungi - reactions (in the bacteria) are happening faster (to decay milk)
- (because there is) more (kinetic) energy
allow particles move faster
allow more collisions between particles - enzyme activity is higher (at 10 °C than at 5 °C)
Suggest two reasons why the different types of milk took different lengths
of time to reach pH 5.
- different concentration / type of fat / lipid
allow different amounts of fat / lipid - different concentration / type of proteins / carbohydrate / sugar
allow different amounts of proteins /
carbohydrate / sugar - different (amount / type of) bacteria present
- may have been pasteurised by a different process
allow may have been treated in different
ways (before the investigation) - different starting pH
ignore different oxygen concentration
Which two types of organism cause decay?
bacteria
fungi
Give one environmental factor needed for decay
water
Gas X is the main fuel gas found in the biogas.
What is gas X?
methane
The dead plant material in the compost heap and biogas generator does
not decay completely.
Explain why a farmer might spread the remaining dead plant material onto
his fields.
so plants / crops grow faster / better
(decays further and) releases / contains mineral ions / named
example
Suggest why a large surface area to volume ratio is an advantage to an
earthworm.
(earthworm) can absorb more oxygen (in a given time)
increases / more gas exchange
Which type of enzyme would digest fats
lipase
Dead plants decay faster in soil containing earthworms compared with soil
containing no earthworms.
Explain why
more oxygen (in soil with earthworms)
allow earthworms bring oxygen to soil
(for) more (aerobic) respiration
do not accept anaerobic respiration
(of) bacteria / fungi / microorganisms / microbes / decomposer
Explain why the students used water on one side of the lawn instead of
weed killer
as a control / comparison
Suggest one improvement the students could have made to the method to
make the results more valid.
use more quadrats
original may not be representative or reference to weeds being
distributed unevenly
Light intensity affects the number of dandelion plants that grow in an area.’
(c) Plan an investigation to test this hypothesis.
- placing of quadrat
- large number of quadrats used
- how randomness achieved − e.g. table of random numbers or
random number button on calculator or along transect
AQA Biology GCSE - Organisation of an Ecosystem
PhysicsAndMathsTutor.com
Page 12 of 19 - quadrats placed at coordinates or regular intervals along
transect - in each of two areas of different light intensities or transect
running through areas of different light intensity - for each quadrat count number of dandelions
- for each quadrat measure light intensity
- compare data from different light intensity
Give two other environmental factors that affect the growth of dandelion
plants.
any two from:
* temperature
allow heat
* water
allow moisture / rain
* (soil) pH
allow acidity
* minerals / ions
allow e.g. magnesium ions or nitrate
allow salts / nutrients
* winds
* herbivores
Give one reason why the students sterilised the flask before adding the
milk.
to kill microorganisms on / in the flas
Describe how the students could sterilise the flask in a school laboratory.
heating
1
to over 100 °C
Why did the students put a cap on top of the flask?
to prevent microorganisms entering from the air
Describe two features of the sprinkler bed that encourage aerobic
respiration.
- sprinkled through air
- air spaces between stones
- thin layer over stones (for efficient diffusion)
- slow flow (for efficient diffusion)
Figure 2 shows that the bacteria change organic matter into carbon
dioxide and inorganic mineral ions.
Describe how the bacteria do this.
- (external) enzymes released
- role of enzymes – e.g. amylase / protease / lipase
- substrates & products – e.g. starch ⟶ sugar / protein ⟶ amino acids
/ fat ⟶ fatty acids
absorption: - by diffusion / active transport
deamination: - amino acids ⟶ ammonia / ammonium ions
release of other ions: - e.g. phosphate / nitrate / magnesium
respiration: - produces carbon dioxide (+ water)
or
equation is given - release of energy allows other processes to take place e.g. active
transport
An airtight compost heap causes anaerobic decay.
Explain why the gardener might be against producing compost using this
method
methane is produced
which is a greenhouse gas / causes global warming
Explain how the carbon is recycled into the growth of new leaves.
- (carbon compounds in) dead leaves are broken down by
microorganisms / decomposers / bacteria / fungi - photosynthesis uses carbon dioxide
explanations: - (microorganisms) respire
- (and) release the carbon from the leaves as carbon dioxide
- plants take in the carbon dioxide released to use in photosynthesis to
produce
glucose
use of carbon in growth: - glucose produced in photosynthesis is used to make amino acids /
proteins / cellulose - (which are) required for the growth of new leaves
Give three possible reasons that may have caused strawberry A to
decay.
- (at) higher temperature / hotter
- (had) more oxygen
- (had) more water / moisture
- (contained) more microorganisms (that cause decay)
The biomass of mackerel is much less than the combined biomass of krill
and squid.
One reason for this is that the mackerel cannot digest all parts of the krill
and squid.
Give two other reasons.
non-eaten parts (of squid / krill)
- respiration or respiring (in mackerel)
makes / creates energy
* excretion (by mackerel)
Explain how making dog food from insects could improve human food
security in the future.
less land required
(so) more space for crops (for humans)
allow more meat (from cows etc) for
humans
less methane (from animals) therefore less global warming
