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Got to ecology questions 1997
1995 1993
Introduction
"The past is the key to the future".
The biology syllabus has remained basically
unchanged since 1969. The last, and very minor revision
of the syllabus was in 1976. The biology examination paper
has not changed since its beginning in 1971.This year,
2000, will be the 30 th. Biology examination. After 30
years there is very little new to ask.
The biology 2001 exam will not present any
problems if you understand and know the answers to the'
old exam papers'. Initially you are offered 10 years of
solutions. This will be built on gradually to extend your
range of expertise increasing your competence in biology.
The solutions are only part of the service.
Also provided are insights to reading, interpreting questions
and answering technique. Poor answering skill is a major
problem. Frequently, answers contain a lot of impressive
and detailed Information but score badly as it is not
directly connected with the question. You must develop
good answering technique so the time you have spent studying
is fully rewarded. A good way to acquire answering skill
is by example. Follow the advice that accompanies each
solution and apply the techniques to your written homework
and class tests. (See advice on 'Success in Exams in the
Study Skills Package).
Question + Solution
Outline how the structure of the alimentary canal of a
mammal is adapted for carrying out its functions. 1987
35 marks Time: 15 minutes
Key words: outline structure adapted functions
Outline: give a concise summary, give the principle
points - minor details are not required.
Structure: the physical interconnecting parts or
framework of the alimentary canal - not processes, not
juices.
Adapted: is suited to, fitting it well - state
how the named part is carries out its role successfully
and or efficiently
Functions: its role or purpose or task or job or
business.
Manor Answer Problems:
1. Students did not pay attention to the word 'structure'.
Named digestive juices but not the glands or organs which
secreted these juices. Named peristalsis but not the muscles
in the wall of the alimentary canal.
2. Missed one major function - control the movement of
food along the alimentary canal.
3. Answers were too long - went well beyond the' budget
time's their last question in the exam was left short
of time.
4. The liver and pancreas are not part of the alimentary
canal - they are accessory organs, outside the canal.
They could be included if the question had stated the'
digestive system'.
Answer
The major functions of the alimentary canal are digestion,
absorption and the control of movement of food along it.
Digestion is the break-up of the complex food chemicals
into simple soluble absorbable subunits. Chemical digestion
is speeded up the physical digestion of the food into
smaller pieces. The teeth in the mouth and the churning
action of the muscles in the wall of the stomach are responsible
for this breakup. Chemical digestion is by enzymes. Salivary
glands in the mouth secrete amylase, which digests starch
to maltose. Gastric glands in the wall of the stomach
secrete pepsin, which converts starch to peptones, peptides
and amino acids. Cells in the lining of the small intestine
secrete a full array of digestive enzymes e.g. amylase
to digest starch to maltose, lipase to digest lipid to
glycerol and fatty acids, erepsin to digest proteins to
amino acids. Absorption is mostly carried out by the small
intestine. The villi the microvilli and the long length
greatly increase its surface area so absorption is very
efficient. Absorption is fast because the only obstacle
to the entry of nutrients is the thin outer membrane of
lining cells. The dense network of blood capillaries and
lymphatic capillaries in the villi efficiently transport
away the absorbed nutrients.
Food is moved along the alimentary canal from oesophagus
by peristalsis, the action of the circular and longitudinal
muscle in the wall of the alimentary. Specialised sphincter
muscles at opposite ends of the stomach control the movement
of food in and out of the stomach.
Ecology Leaving Certificate Biology: Q
10. 1997
(a) (i) Map of Grassland Habitat
(ii) Plant Distribution Method: Line Transect
Description:
1. Place a rope marked at half metre intervals or a measuring
tape in a straight line across the grassland habitat.
2. Draw this line to scale on the map of the habitat
and mark off the half metres.
3. Walk beside the rope or tape and record on the map
the different species touched by the line at each half
metre.
4. Repeat this twice more, parallel to the first, from
two other suitable start points.
5. Make a separate distribution map for each species
of plant by combining the results of the three line transects.
(iv) Pyramid of Numbers
Fox --------------- 10 ___________Third Trophic Level
Rabbit ---------- 5,000 ___________Second Trophic Level
Grass ------- 500,000,000 _________Third Trophic Level
(v) Abiotic Factors
Non-living agents that influence the community of
a habitat e.g. soil pH.
Biotic Factors
Living agents that influence the community of a habitat
e.g. earthworm soil population.
(b) Species Conservation
Positive action to preserve each species particularly
by protecting their unique habitats.
Reasons for Species Conservation (any three)
1. Maintain the balance of nature - the extinction of
one species could cause the extinction of or drastic population
changes in other species.
2. Survival of our own species - by ensuring a healthy
environment for other species we guarantee a healthy environment
for ourselves.
3. To maintain the supply of beneficial materials from
nature e. g.
(i) food - all our food comes from nature,
(ii) raw materials e.g. timber, cotton, silk, rubber.
(iii) medicine - many of our medicinal chemicals come
from plants.
4. To preserve future benefits - many species have yet
to be examined for possible use as food, medicine or as
a source of raw materials for industry.
5. To maintain genetic diversity
6. Ethical reasons - each human generation should pass
on the biosphere to the next generation in at least as
good condition as it received it.
7. Scientific - each species examined increases our knowledge
of nature.
(c) (i) Pollution
1. Pollution is the contamination of the natural environment
with substances whose quantity or type disrupts the balance
of the natural community of organisms.
2. A pollutant can be a substance not normally found
in the habitat e.g. persistent pesticide like DDT which
kills many non-pest species of insects in the community.
3. A pollutant can be a substance normally present but
is now present in excessive amounts e.g. detritus silage
slurry or human and animal sewage which would lead to
the deoxygenation of ponds rivers and lakes.
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Ecology Leaving Certificate Biology: 1995
(a) (i) Pyramid of Numbers: a diagram that shows
the number of individuals of each species at each trophic
level in a food chain.
Food Niche: the functional role of the organism
is the community in connection with diet; the feeding
habits of the organism; all the environmental factors
that affect the acquisition of food by the organism.
Named Ecosystem: Grassland.
Three Plants: clover, dandelion, daisy.
Three Animals: bee, rat, hawk.
(ii) Two Favourable Factors: Named Plant.
Clover:
1. The soil is low in nitrogen. The clover has nitrogen-fixing
bacteria in its roots.
2. The soil is well aerated so the supply of nitrogen
gas to the roots is good.
(iii) Estimating the Rat Population by the 'capturelrecapture'
method. 1. Set out a big number of small mammal traps.
2. Record the number of captured rats e.g. 40.
3. Mark each rat with a dab of red paint on its abdomen.
4. Release each rat back into the habitat at its capture
site.
5. Set out the traps again the next day or a number of
days later.
6. Record the number of captured rats e.g. 49.
7. Record the number of recaptured rats, marked with red
paint, e.g. 7.
8. Release each rat back into the habitat at its capture
site.
9. Calculate the population as follows
Population = (Number of Day 1 Captures X Number of Day
2 Captures)/ Number of Recaptures .
(40 X 49)/ 7 = 280 rats.
(b) (i) Energy First Enters Ecosystem as: Light.
(ii) Process Converting Light to a Usable form of
energy: Photosynthesis.
(iii) Percentage Energy Lost at Each Transfer:
90%
Significance of Loss:
(a) Food Chain Length: results in short food chains.
(b) Number of Organisms in Final Trophic Level:
small or smallest number.
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Ecology: Leaving Certificate Biology: 1993
Essay: answer must be given in essay form - a logically
consistent short piece of prose.
Brief discussion of any five of the following possible
problems.
Climate
Change
a)
Local: reduced local rainfall due to the loss of trees,
this leads to reduced agriculture.
b)
World-wide: 'global warming', less trees so less carbon
dioxide removed from the air for photosynthesis, therefore
a rise in carbon dioxide concentration in the atmosphere.
Barren
Land
a)
Soil Erosion: rain and wind will erode the soil without
the roots of the trees to bind the soil.
b)
Soil Infertility: removal of the trees removes the vital
mineral nutrients from the habitat.
Extinction
of Species
a)
Loss of Potentially Useful Plants:
(i)
Medicine: many tropical plants are the source of useful
medicinal chemicals, many more have yet to be tested
or retested.
(ii)
Food: some species may have the potential to be of
agricultural interest; man's agriculture will have
a narrower and more vulnerable food base.
(iii)
Timber and other commercial interest:
b)
Loss of Potentially Useful Animals:
(i)
Agricultural value: food source and biological control
of pests.
Increased
Water Runoff
Increased
soil erosion, flooding and sediment buildup in rivers,
lakes and reservoirs.
Scientific
Research
Each
species that becomes extinct is a lost chapter in the
'book of life'.
Recreation.
Destruction
of this habitat results in a loss of a recreational
resource and reduced tourism.
Reduced
Size of the Habitat
The
smaller the area of the habitat the smaller the number
of species it can carry This automatically leads to
the extinction of many species - a ninety percent reduction
in forest cover means the loss of half of the species.
Reduced
Populations
Reduced
genetic diversity within species - less adaptable populations.
Effect
on the Indigenous People
(i)
Reduced population - lack of food, new diseases by new
pathogens carried by immigrants.
(ii)
Migration to new areas.
(iii)
Loss of culture - westernisation and'religious conversion'
of the native people.
Slow
Recovery of the Habitat
Destruction
is almost permanent as tropical soils are generally
very poor because the mineral nutrient and humus levels
are very low.
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