Exam Questions Flashcards
A small, permanent pond is the habitat for a climax community of producers (aquatic plants and algae) and consumers (bacteria, protoctista, worms, snails, arthropods and small vertebrates like newts and fish).
Why might ecologists call this a ‘climax community’?
(pond community is) final / stable / not subject to further succession
The protoctist Paramecium caudatum is usually between 200 and 300 μm in length. An accurate measurement would help in the correct identification of a species from this pond. What laboratory equipment would you select to make an accurate measurement of the length of Paramecium candatum?
light microscope (1) graticule (1)
An animal fell into the pond. It drowned and decayed. Within a year the biological compounds in its body had been completely recycled.
(i) What nitrogenous excretory molecule from the decomposers would pass to the next stage of the nitrogen cycle?
urea / uric acid
ammonia, ammonium (ions)
Explain how the selective breeding that led to this increased yield could have been done.
1 crossbreed / breed / interbreed, high- yielding, wheat plants / individuals
2 assess / test / measure, yield / AW;
3 crossbreed / AW, selected / best / high-yielding, offspring;
4 over generations
5 marker assisted selection / prevent self-pollination / genetic screening / prevent unwanted (cross) pollination
State two developments, other than selective breeding, that could account for the total increase in wheat yield per hectare.
(use of) fertiliser;
(use of) pesticide / fungicide / insecticide;
improved technology;
Using Fig. 2.1, describe the pattern shown by the data for the estimated number of live elk from 1965 to 2002.
1 peak in, 1988 / 1994;
2 trend decrease after 1994;
3 ref. decrease and then increase, 1988 to 1994;
4 fluctuations (within pattern);
5 overall increase from 1965 to 2002;
The recorded number of elk legally shot by hunters provides accurate data.
Suggest why these data are accurate, but the method used to obtain these data is not a valid way of estimating the number of elk in the population.
[3]
accurate because
idea that actual number of elk shot is recorded;
method not valid because idea that number of elk shot / hunting success, varies independently of population size
CREDIT suitable reason
e.g. numbers of licences issued / number of hunters
set quotas to hunt
illegal hunting
if weather suitable for hunting
only younger / older / diseased / larger, elk killed
The grey wolf, Canis lupus, is a large predator whose diet includes elk.
By 1926, grey wolves had been hunted to extinction in Yellowstone Park. However, this species could still be
found in other parts of the world.
In 1995, a population of grey wolves was introduced to Yellowstone Park and their numbers increased.
(i) With reference to Fig. 2.1, discuss the factors that may have affected the size of the elk population:
before 1995 after 1995.
In your answer you should provide a balanced account referring to factors before and after 1995.
1 idea that population size is determined by limiting factor(s);
Before 1995, population increases due to
2 example of factor that is not limiting population;
Before 1995, population levels off because
3 reaches carrying capacity;
Before 1995, population becomes limited by
4 intraspecific competition for named resource;
5 interspecific competition for named resource;
Population can decline at any time/ dips, due to
6 severe weather / natural disaster;
7 decrease before 1995 not due to wolves
(as none present);
8 decrease after 1995 (probably) due to wolves;
9 idea that effect of wolves on population may be debatable;
Explain why the introduction of wolves to Yellowstone Park in 1995 is an example of conservation.
1restoring the ecosystem (to its original form)
or
maintains biodiversity;
2helps the (global) wolf population;
3active / dynamic / sustainable, management / maintenance;
4prevents over-population by the elk;
5prevents over-grazing
or
damage to, habitat / ecosystem
The efficiency of energy transfer between trophic levels limits the number of organisms in a particular ecosystem.
Outline how the percentage efficiency of energy transfer between producers and herbivores can be estimated.
Describe the differences between the following biological terms: a pioneer community and a climax community
1 pioneers arrive, before climax / earlier; ora
2 pioneer communities subject to, greater / more, change / succession / replacement; ora
3 pioneer community (usually) has, less / lower, biodiversity; ora
4 idea that pioneer community is (often) less, stable / self-sustaining; ora
5 pioneer community has lower biomass; ora
6 AVP;
Describe the differences between the following biological terms decomposition and denitrification
1 decomposition is break down, dead matter / waste
or
decomposition is conversion of organic matter to inorganic;
2 denitrification is conversion of nitrates to nitrogen (gas);
3 decomposition increases, mineral / nitrate, supply
and
denitrification reduces, mineral / nitrate, supply;
Describe the differences between the following biological terms: nitrogen fixation and nitrification
1 nitrogen fixation is the conversion of (atmospheric) nitrogen into, ammonia /
ammonium compounds / ammonium ions;
2 nitrification is the conversion of, ammonia / ammonium compounds / ammonium ions, into nitrite / nitrate;
3 correct ref to microorganisms involvement in both processes
A student investigated the distribution of buttercups (Ranunculus bulbosus) in a field which contained a pond. The student noticed that the buttercups near the pond looked slightly different from those further away. After further investigation the student identified the buttercups near the pond as a different species (Ranunculus repens).
(i) Describe how the student would use a belt transect to investigate the distribution of the two buttercup species.
lay tape measure out from edge of pond ✓
place quadrat beside tape measure ✓ identify species of buttercup in quadrat ✓
count number of plants of each species (in quadrat) ✓
repeat for positions of quadrat along tape ✓
As the ground dipped towards the pond the soil became obviously wetter. The student thought that the soil moisture might affect the distribution of the two buttercup species.
Suggest one biotic factor that might affect the distribution of the buttercups.
predation / herbivory ✓
competition ✓
correct ref to organisms living in soil ✓
