ECOLOGY B.Pharmacy 2nd Semester 2023 (2022-2023) Previous Year's Question Papers/Notes Download - HK Technical PGIMS

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ECOLOGY
Ecology is the scientific study of the interaction between organisms and components of
their environment.
Synecology is the ecological study of the different species.
Autecology is the ecological study of a single species.
Ecological levels, from the smallest to the largest:
 Habitat: a place where an organism lives.
 Population: a group of organisms of the same species living together in the
same habitat.
 Community: a group of populations living in a prescribed area or habitat. This
 is a naturally occurring group of organisms of different species,
 inhabiting a common environment and interacting with each
 other, especially through food relationships and which is
 independent of other groups.
 Ecosystem: is any unit of the environment, composed of living and non-living
 components whose interactions result in a stable system.
 Biome: is a collection of similar communities in a certain large area of the earth,
 where climate and topography are fairly uniform.
 Biosphere: is that part of the earth and its atmosphere which is inhabited by
 living things.
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ECOLOGICAL FACTORS
Ecological factors are divided into two: physical or abiotic (non-living) and biotic
(living factors).
1. Physical (or abiotic) factors:
a) Climatic factors:
i) Precipitation: this refers to the amount, reliability, distribution and
seasonality of rainfall and all these are important aspects of climate.
ii) Humidity: often expressed as Relative Humidity (RH). It is a measure
of moisture content of the atmosphere, expressed as a percentage of
the quantity of water present in a given volume of air in relation to
maximum quantity of water the air can hold at the same temperature.
Note that RH is influenced by temperature.
iii) Light: both quality (effect of the different wavelengths, e.g. UV, blue,
etc) and quantity.
iv) Temperature: temperature is important for enzyme activity in living
cells. It also affects the rate of transpiration and evaporation.
v) Air/Water currents: Water currents would include both vertical and
horizontal currents. Horizontal currents are for example in the transfer
of algal cells, where if the previous day’s currents blew towards the
shore, the following morning, the water along the shore is all green.
When strong winds blow away from the shore, the water clears
because the algal cells have been transferred away from the shores by
the horizontal currents.
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b) Edaphic (or soil) factors: these are the physic/chemical factors which affect
soil and hence, plant and animal life.
i) Soil organisms: for example, soil micro-organisms, like bacteria, algae
and fungi, which affect the soil turn-over and hence, aeration.These
organisms affect seed germination by breaking seed dormancy. They
also contribute to N-cycling as N2 fixers (for example, some bluegreen algae, the Cyanobacteria).
ii) Soil moisture: affects supply of water and minerals; also seed
germination as a necessary factor. But too much of it may render the
soil water logged
iii) Soil texture: this refers to the size of the particles and their fractional
proportions. This affects soil aeration, water content and thus, soil
productivity.
iv) Soil structure: this is the arrangement of the soil particles, which has an
effect on drainage, percolation, erosion and aeration.
v) Soil temperature: this affects soil formation, respiration of organisms
and N2 fixation. It also influences seed germination and root growth.
vi) Soil pH: this affects the activity of the soil microorganisms, solubility of
solutes, e.g. PO4, Mg, Ca and Fe. It also influences distribution of
vegetation.
vii)Soil aeration: this is the amount of air in the soil which depends on soil
texture, water content, and amount of humus present in the soil.
c) Topographical factors: which are factors which are controlled by altitude,
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 slope and other geographical aspects of the place.
Abiotic factors of aquatic ecosystems, e.g. Lakes:
 Salinity
 Wave action
 Water currents, both vertical and horizontal
 Light: quality and quantity and its penetration
 Nutrients, e.g. N, P, Si, etc.. and their ratios, e.g. the N:P ratio.
 O2, CO2 concentration and pH.
Fires as an ecological factor:
Fires have both positive and destructive effects.
Positive effects of fires:
 Breaks seed dormancy in some species, e.g. Acacia.
 Destroys pests and parasites, e.g. ticks of cattle.
 Etc.
Negative effects of fires:
 Removes vegetation cover, leading to soil erosion.
 Destroys some organisms important in the habitat.
 Destroys humus and the soil.
 After a fire, some seeds of unwanted plant species may invade the area
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2. Biotic ( or living or biological) factors:
These are factors resulting from the effects of the living organisms on one another within
a habitat where they live. Such interactions may result in associations like: predation,
commensalism, symbiosis, herbivory, competition (intraspecific or intespecific) , etc.
Humans as important biotic factors:
Through his activities in trying to make a living, man has affected the lives of other
organisms through such activities like:
 habitat destruction for: settlement, road construction, agriculture, etc..
 pollution of many natural ecosystems: rivers, lakes and land, through his use of
radioactive materials in warfare, oil leaks, nuclear reactor disasters.
 Destruction of the ozone layer (how)
 Over-exploitation of natural resources (e.g forests, etc.), leading to the
greenhouse effect (global warming).
The greenhouse effect (Global warming):
CO2 concentration
Photosynthesis Respiration Combustion Volcanic eruptions
Note:
 Carbon dioxide is the least gas in the atmosphere (0.04%)
 It is used for photosynthesis by plants (forests and other vegetation)
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 It is availed to the atmosphere through activities like respiration, combustion
and volcanic eruptions.
 Carbon dioxide uptake and release are not in balance: its release into the
atmosphere tends to be higher than its uptake (which is only through
photosynthesis). Thus its concentration to continuously increase. Carbon dioxide
is transparent to incoming, visible solar radiation, like glass (in green houses). It
absorbs infrared heat re-radiated from the earth’s surface and therefore CO2
forms a heat blanket by shielding heat from earth back into the outer space
and therefore this increase in heat results in increasing temperatures on the globe
(earth’s surface). This phenomenon is referred to as ”the Green House effect or
 Global warming”. Thus, Man’s activities increase CO2 concentration when he
cuts down forests and other vegetation which results in reduction of CO2 uptake
by photosynthesis. Also his burning of fossil fuels increases CO2 concentration.
POLLUTION
Pollution is the act of introducing harmful substances/impurities to the environment as a
result of human activities and/or other natural processes. Pollution can be by biological,
chemical or physical agents. Pollution remains a major cause of ill health in rural, periurban and urban areas. Increase in human population and urbanization has caused more
production of domestic and industrial wastes and such wastes have become a major
pollutant of the environment.
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Human activities such as industrialization, have resulted in the production of chemicals
which include heavy metals and products from the petroleum industry. Human waste,
agricultural chemicals, e.g. herbicides, insecticides, etc. have worsened the situation.
Such pollutants finally reach and pollute the food chain, surface waters (lakes, rivers,
wells, etc.) or ground water and can finally be ingested by humans.
Types of pollution:
 Air pollution: this is the discharge of foreign gases, dust, fumes, electromagnetic particles, noise, pollen from industrial, agricultural and domestic
processes, vehicles, military explosives and smoke; all the above into the
atmosphere.
 Water pollution: this is as a result of discharge of effluent from: factories,
industries, agricultural fields, sewage treatment plants, wastes from homesteads,
spilling over filled latrines into water bodies. Also the introduction of heavy
metals, e.g. CU, etc., pesticides, herbicides, insecticides into water bodies.
 Ground pollution: this results from disposal of solid waste, e.g. polythene bags,
etc., liquid wastes and gaseous wastes. Other ground pollutants include:
radioactive wastes, medical wastes, wastes from research laboratories, industrial
wastes, agro-chemicals and raw sewage.
Pollution of food staff and water bodies can cause diseases like cancer, chest infections,
suppression of body immunity and destruction of plant and animal life. Pollution can also
cause degradation of land and other natural resources. It can also bring about offensive
smells irritation and discomfort. Land pollution can also promote the spread of parasitic
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worm infection whose eggs flourish in the soil. It can also facilitate the survival and
growth of disease-causing organisms.
Preventive measures of pollution:
1. Avoid discharging pollutants in the environment.
2. Urban areas should be well planned and designed and these plans and designs
should be adhered to.
3. Test all imported and locally manufactured chemicals.
4. Treat all categories of wastes before disposal.
5. All laws and regulations governing pollution should be strictly enforced.
6. All industrial workers should strictly use protective gear.
POPULATION DYNAMICS
Every population has its own unique properties:
a) Density: is the number of individuals per unit area.
b) Mortality (or Death) Rate: is the number of individuals dying in a given time.
It is usually expressed as /1000 individuals of the population / annum.
c) Birth (or Natality) Rate: is the number of individuals born in the population in
a given time. It is also expressed as a percentage (%) or /1000 people /year.
d) Age distribution or structure: is the proportional distribution of individuals of
various ages in a population and this gives a future trend of that population
growth. For example, if a population has most of its individuals as youths, that
population is likely to grow or increase very fast.
This is shown in the following diagrams: (p. 9 notes)
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e) Dispersion: is the structural distribution of individuals within a given area.
f) Biotic Potential: is the maximum rate at which members of a population
(species) can reproduce within the available resources and living conditions
g) Growth Form: is the variation in apopulation size with time. Growth may
exponential, giving a J-shaped curve or it may be sigmoid.
Nos Nos
Time Time
 J- Curve Sigmoid Curve
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ENERGY FLOW IN AN ECOSYSTEM (Simplified)
Food relationships in an Ecosystem:
1. Food chain: this is a linear nutritional relationship in which one organism eats
another and is also eaten. It can also be a transfer of food energy from it source in
green plants through a series of organisms with repeated eating and being eaten.
a) Grazing Food chain:
E.g. Grass Grasshopper Snake Owl
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0
Producer 1
0 Consumer 2
ndry Consumer 3
tiary Consumer
1
0 Trophic level 2
nd Trophic level 3
rd Trophic level 4
th Trophic level
Trophic levels refers to a feeding level within a nutritional relationship.
Energy Flow from
the Sun
Energy fixed in
Photosynthesis
(Primary Producer)
Primary Consumers
Secondary Consumers
Tertiary Consumers
Energy Loss to
Detritus
Heat Loss in
Respiration
Decomposers
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b) Detritus Food chain:
E.g. Organic matter Microorganisms Detritus Feeders Predator
 c) Food Web:
Mountain Lion
Mice Foxes
Predatory Birds
Insects Fish Deer Birds Rabbits
Green Plants
In this case, each organism is a member of a number of different food chains.
Terms relating to energy production and transfer:
1. Primary Production: is the amount of energy which primary producers fix in
form of organic matter , expressed in terms of:
 Unit Mass / Unit Area/ Unit Time
E.g. Kg / Km2
/ Year or Kg Km-2 Yr-1
a) Gross Primary Production (GPP): is the total amount of energy fixed by
1
0
 Producers in photosynthesis / unit area / unit time.
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c) b) Net Primary Production (NPP): is Net Assimilation of energy by plant
tissues. This excludes that portion used by the plant in its own respiration and
represents the energy available to the 10 Consumers.
Thus: GPP – Respiration = NPP
2. Biomass: is the mass of organisms per unit area of ground (or water). It is
expressed (usually) as Dry mass / Unit area E.g. Tonnes / Hactare
or as Energy / Unit area E.g. Joules / m
-2
.
3. Standing Crop: is the Dry weight (energy content) of organisms in an area at a
particular time.
4. Secondary Production: is the rate of production ….?
5. Trophic Efficiency: is the amount of energy that a trophic level can convert into
organic tissue. It is usually 10% of what it receives from the previous trophic
level.
ECOLOGICAL PYRAMIDS
Ecological pyramids are histograms used to show how various ecological factors
diminish with the trophic level.
1. Pyramid of Numbers: is a histogram showing the proportions of number of
organisms aat various trophic levels in a food chain. It shows a progressive
decrease in numbers, from the producers to the final consumers.
2. Pyramid of Biomass: is a histogram showing the proportion of biomass of
organisms at various trophic levels in the food chain.
3. Pyramid of Energy: is a histogram showing the proportion of energy
available in organisms at various trophic levels in the food chain.
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FACTORS AFFECTING A POPULATION
1. Density-dependent Factors: are factors of the environment whose effect
depends much on the population size. Examples of such factors include:
 Food shortage
 Competition
 Diseases, e.g. epidemics
 Pollution due to accumulation of waste
 Psychological effects of overcrowding on the reproductive rate (lower
production of people are overcrowded) ???????
2. Density-independent Factors: are factors factors of the environment whose
effect does not on the size of the population. Examples of such factors
include:
 Rainfall
 Light
 Nutrients in the soil
 Drought
 Fires
 Floods
 Natural catastrophes like landslides, accidents, etc..
ECONOMIC IMPORTANCE OF ALGAE
1. Positive importance of algae:
 Algae are primary producers
 Algae are used as food for fish and higher animals
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 Algae are used as food by humans, e.g. sea food eaten by the coastal
people
 Diatomite earth: a type of rock resulting from deposits of the heavy diatom
cells which form a white, porous and chemically inert rock used for
filtration processes (in breweries and sugar refineries), also as a
constituent of tooth paste and explosives.
 Alginic acids extracted from the cell walls of brown algae readily reacts
with anions (e.g. Mg, Na, etc) to form highly viscous gels used as food
thickeners in ice creams and diary products; as a constituent of cosmetics
and shaving creams and also in the making of artificial teeth.
 Agar powder, extracted from the cell walls of red algae, is used as a
culture medium for bacteria, fungi and algae; as food thickeners like
alginates; also as a component of cosmetics, ointments and lotions and as
an anti-drying agent in bread; and as a component of cheese, puddings,
creams and jellies; etc..
 Algae also act as biological indicators of the extent of pollution of aquatic
ecosystems, e.g. as shown by presence of blooms of ‘blue-green’ algal
species.
 Algae are much used in research (e.g. Space research and paleo-ecology of
aquatic ecosystems, using diatom cells, together with pollen grains)
 Algae as fertilizers (dead algae add organic matter to the environment) and
some ‘blue-green algal’ forms capture N2 and incorporate it in the
ecosystem.
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Negative importance of algae
 Some ‘blue-green algal’ forms produce toxins: hepatotoxins, neurotoxins
and dermatotoxins which affect humans and may be lethal.
 Algal blooms cover water surfaces, reducing light penetration which leads
to competition for light and some cells die and sediment to the bottom and
their decomposition leads to reduction in O2 which could result in ‘fish
kills’, bad odour, colour and taste.
 Algal forms that are slippery, like Spirogyra spp covering ground/rock
surfaces causes accidents to cattle and humans.
 Algal cells also coat water containers, like jerrycans.
ECONOMIC IMPORTANCE OF BRYOPHYTES AND FERNS
Bryophytes include liverworts and mosses and their economic importance include the
following:
 Bryophtes act as primary producers
 Bryophytes provide seed-beds for higher plants.
 Ecologically, many bryophytes are pioneer plants on bare rock.
 Liverworts produce volatile oils, which have a potential as anticancer and
anti-microbial chemicals.
 Ferns are also primary producers; food for animals and provide manure
when they rot.
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ECONOMIC IMPORTANCE OF GYMNOSPERMS
Examples of Gymnosperms include the conifers and the common examples of conifers
include Pinus, Cuppressus, Casuarina (X-Mas tree), etc. Their importance include the
following:
 Gymnosperms are important as forest trees, e.g. the Coniferous forests, in
the Government forests, e.g. where Pines dominate and these forests
reduce soil erosion and are also important in rain formation.
 Some species of Gymnosperms, e.g. the Cycadales are used as human
food as a source of starch.
 Some Gymnosperm species produce Essential oils, used as perfumes for
scenting soaps. Canada balsam is a type of thick oil used as mounting
medium in microscopy when making permanent slides (it does not
crystallize nor granulate on drying). Canada balsam is also used to fix
lenses in spectacle frames. Cedar oil from Juniperus virginiana is used as
immersion oil.
 Gymnosperms as drugs: the alkaloid drug Ephedrine is extracted from
the green branches of Ephedra sinica and E. equisetina. This drug is an
important constituent of cough mixtures; it dilates bronchial tubules and
also contracts mucous membranes and it is, thus used in nasal drops and
inhalents Extracts from Ginkgo biloba are used to treat cerebral
inefficiency (poor memory), an is sold as ‘Ginkgo’ by Food Supplement
Companies, e.g. Swissgarde, House of Health, Tianshi, etc.. Extracts from
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leaves of Taxus baccata and are used to treat asthma, bronchitis, epilepsy,
indigestion and hiccough.
ECONOMIC IMPORTANCE OF ANGIOSPERMS
Angiosperms as medicinal plants: Medicinal plants and plant-derived medicines are
widely used in traditional cultures all over the world and have become very popular in
modern society. They are being used side by side with synthetic chemicals (Western
medicine). Natural products and their derivatives make more than 50% of all drugs in
clinical use in the world. Examples of plant-derived medicines include:
 Quinines
 Morphine
 Codein
 Colchicines
 Atropine reserpine
 Digoxin ( for improving heart-bit – it digitalizes the heart
Plant extracts may be flavours, spices, dyes, perfumes, stimulants, bio-pesticides (e.g.
fungicides, anti-virals, insecticides, herbicides, etc).
Pharmacognosy is the study that deals with the identification of medicinal plants and
drugs therefrom and the study requires botanical, anatomical and phytochemical
knowledge. In traditional cultures, plant products are used in combination with
psychological treatment in an integrated approach to primary health care. The
psychological part of the treatment takes the form of magical, ritual and spiritual
approach.
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Examples of medicinal plants commonly used:
 Acacia Senegal (Gum Arabica): A small, thorny shrub in arid regions, up to 6m
high. The part of the plant used is the exudate from the stem. It is used to protect
the skin and mucosa and also to treat bacterial and fungal infections of the skin
and mouth. The product may be applied directly on the skin or included in the
formulations and tablets. Gum Arabic is a complex polysaccharide, containing
galactose, etc..
 Allium cepa (Onions): Parts used include bulb and leaves, used as antibiotics to
lower cholesterol, to treat appetite loss, digestive disorders, insect stings, etc..
When mixed with honey, it treats colds and cough. It can also treat dysentery,
scars, asthma and diabetes and can also lower pressure.
Preparaation:
- 50 g of fresh onion or 20 g of dried product
- Raw bulb may be applied directly
- Or extract may be mixed with honey or add sugar.
N.B. The pungent smell of onions is due to S-containing compounds.
 Allium sativum (Garlic): Parts used are bulbs, garlic powder, or garlic oil. Garlic
lowers lipid and is also antibacterial, antiviral and also cures common colds. It is
best used when fresh. Garlic powder can also be carefully prepared. Tinctures and
syrups can also be prepared.
 Aloe spp (e.g. A. vera, A. ferox, etc..) Whole leaf may be crushed and extract
obtained. It is used to heal wounds, also for skin care, tonic drinks, etc.. E.g. 50 –
100g of gel x 3, daily.
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 Ananas comosus (Pineapple): Pineapple juice is used as digestive tonic, cures
inflammations. Juice contains enzymes, collectively known as Bromelains; also
Vit C and Caffein.
 Artemesia spp This is a herbaceous plant whose extracts have antimicrobial
properties, cures coughs, malaria, colds, sore throat, influenza, asthma, headache,
indigestion, constipation, intestinal worms, etc.. Fresh or dried leaves are used;
leaves may be boiled in water and used as steam bath and fumes inhaled or fresh
leaves may be inserted in the nostrils to treat a blocked nose.
ANIMALS AND HUMAN DISEASES
People’s health is always under threat from organisms that carry disease-causing agents.
The biggest impact on health and longevity of people has resulted from a better
understanding of the causes of diseases. Examples of the animal groups that are
associated with human diseases:
Invertebrates:
Phylum Platyhelminthes: (Flat worms)
- Class Trematodes – the flukes, e.g. the liver flukes in domestic animals,
like cattle
- Class Cestoda – the tape worms, e.g. Taenia spp (T. saginata, T. solium)
 Phylum Nematoda: (Round worms)
- The Nematodes
- The Round worms, e.g. Ascaris
 Phylum Mollusca: (Snails and slugs) Snails are important vectors of parasites that
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cause human diseases. Example is the snail Biomphalaria, an
intermediate host of Bilharzia (Schistosomiasis).
 Phylum Arthropoda: With various classes of organisms that transmit parasites that
cause human diseases.
- Class Insecta: This includes different types of insects: cochroaches,
houseflies, mosquitoes, tse-tse flies, beetles, butterflies and moths, and the
stinging wasps and bees.
Below is a table, showing various vectors and the diseases associated with each vector:
VECTOR DISEASE
Anopheles Mosquito Malaria
Housefly Dysentery, Cholera, Trachoma
Tse tse fly Sleeping sickness
Flea Plague
Cockroach Typhoid
Lice Typhus
Dog Rabies
Birds Bird flue
Etc…. ….

The damage to crops by locusts and grasshoppers can also cause problems to humans.
Termites are another nuisance to humans, although they are eaten and have high protein
content.
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ECONOMIC IMPORTANCE OF FUNGI
Positive importance:
1. As research tools: fungi are used in the study of the laws of genetics, e.g. Genus
 Neurospora: biochemistry and cytology
2. Preparation of organic acids: an example is Cytric acid and gluconic acid which
 are commercially produced from Aspergillus niger. Fumaric and Lacti acids are
 produced from Rhizopus stolonifera.
3. Fungi in various industries: e.g. bread-making (yeasts), wine-making (yeasts),
 beer-making (Saccharomyces spp., cheese-making (Penicillium spp.), etc..
4. Production of antibiotics: e.g. penicillin obtained from Penicillium spp.,
 griseofulvin (a fungicide against skin fungal infection) extracted Penicillium
 grisiofulvum.
5. Enzymes and vitamins: Vitamin B complex and Riboflavin are extracted from some
 Saccharomyces spp; ergosterol (containing vitamin D) is extracted from a number of
 moulds and yeasts.
6. Hormones: E.g. the plant hormone: Giberellin (which accelerates plant growth) is
 extracted from some species of Gibberella.
7. Fungi as insecticides: Many fungi attach a number of insects which attack
 plants/crops and thus relieve man of these dangerous insects.
8. Fungi as food: edible mushrooms, e.g. Agaricus spp. This has the types that are
 cultivated and such fungi have a high protein and vitamin content. Some species of
 Saccharomyces are used in the production of yeast cake.
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Negative importance of Fungi:
1. Human diseases:
. Aspergillosis is a human disease with symptoms like those of TB and is caused
 by Aspergillus niger and A. flavus.
 . Infections of lungs, brain and gastric tissues are caused by some species of
 Rhizopus and Mucor.
 . Skin infections, e.g. skin infections of the penis is caused by Trichophyton spp.
 . Ringworm infections: common in children and locally referred to as Bisente or
 Mashiringi.
 . Candidiasis: attacking skin, oral cavity and vulva. It causes a lot of itching and
 the fungus responsible is Candida albicans.
 Note that fungal infections are difficult to cure because there are a few non-
 toxic antifungal compounds known . There is also the
 problem of ‘wrong treatment’ (e.g. treatment before lab tests are done): where
 for example a patient infected with a fungus does self-treatment with an
 antibiotic instead of a fungicide.
2. Spoilage of food and stored grains:
For example, Aspergillus, Rhizopus, Mucor, and Penicillium are commom food-
 spoiling fungi. Species of Ascomycetes and Deuteromycetes (Imperfect Fungi)
usually attach food grains stored in places with high humidity.
3. Crop diseases:
The notorious coffee/banana wilt, e.g. Hemileia vastatrix causing coffee wilt.
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 Phytophthora annamoni attacks Eucalyptus. Fusarium spp. attack bananas,
causing banana wilt. Fusarium lycopersicum attacks tomatoes.
4. Mushrooms very poisonous to humans:
Some species of fungi (mushrooms) are very poisonous and sometimes cause
death to humans.
5. Wood fungus:
Wood-rotting fungus attack wood, breaking down the wood components and thus
reducing its mechanical strength. This causes monetary losses.
6. Fungi causing problems in aircrafts and fuel tanks:
Certain fungi grow in fuel tanks containing kerosene-based fuel. These fungi form
hyphae which can block pipes, leading to fatal accidents to the aircraft.