Ecology 1st year Topic 9

Question 1

Define ecology

Answer 1

The study of how organisms are affected by their environment and by other organisms

Question 2

Define population

Answer 2

It is a group of individuals living together in a particular geographical area at the same place at the same time and can interbreed.

Question 3

Define habitat

Answer 3

It is a specific locality within an ecosystem which contains a particular set of environmental conditions and its own particular adapted community of organisms.

Question 4

Define species

Answer 4

A group of living organisms that are able to interbreed with each other to produce fertile offspring. These fertile offspring will not produce “viable” offspring with members of a different species.

Question 5

Define a community

Answer 5

A group of naturally occurring populations of different species that lives together and interact as a self-contained unit in the same habitat.

Question 6

Define an ecosystem

Answer 6

The ecological system based on the relationship between all the living organisms and the non-living component of the environment within which they occur naturally.

Question 7

Define the biosphere

Answer 7

All ecosystems on earth make up the biosphere.

The biosphere consists of all the total volume, of air, land and water that supports life around the earth’s surface.

Life in the biosphere depends on the sunlight’s energy, on the circulation of heat and on essential nutrients.

Question 8

What is an ecological niche?

Answer 8

It refers to the functional role of an organism within an ecosystem

Question 9

Define a biome

Answer 9

A biome is a large ecosystem defined by its distinctive vegetation, animals, and climate, influenced by abiotic factors like light, wind, soil, rainfall, temperature, and nutrients. Examples :grasslands

Question 10

Define food chain

Answer 10

A food chain shows how energy is passed on from 1 organism to another by showing what each organism eats.

(When 1 organism feeds on another)

Question 11

Give 3 examples of food chains

Answer 11

Grass: grass hopper: frog:snake

Sun:grass:slug:sparrow

sun:mosses:slug:devil’s coach horse

Question 12

Distinguish between prey and predator

Answer 12

Prey: the organism which gets eaten

Predator: the organism eating the prey (eater)

Question 13

Distinguish between producers
primary consumer
secondary consumers and tertiary consumers

Answer 13

producers: they are usuually autrotrophic organisms

Primary consumer
secondary consumer
tertiary consumer

Question 14

Define trophic level

Answer 14

It is any of the feeding levels from which energy passes through, as it proceeds through the ecosystem

Question 15

Define a food web

Answer 15

It consists of many interacting food chains. It shows the flow of energy and the decomposers involved

Organisms can feed on more than one organism

Question 16

What is the role of plants in food chains or food webs?

Answer 16

Plants they absorb sunlight energy in order to convert carbon dioxide and water into glucose and oxygen through the process of photosynthesis which occurs in the chloroplast

Question 17

Why are food webs important?

Answer 17

Food webs are important because if one of the consumer’s food source dies, then the consumer will have another food source available ensuring survival for that consumer

Question 18

Define competition

Answer 18

The struggle for the utilization of resources such as food,light,space,mating,companions,oxygen or carbon dioxide etc.,by one or more organisims of the same species (intra-sepcific competition,or by diffrent species (inter-specific competition),that are living together in a community

Question 19

Define intra-specific competition

Answer 19

The struggle for the utilization of resources such as food,light,space,mating,oxygen or carbon dioxide etc by one or more organisims of the same species that are living together in a community

Question 20

Define inter-specific competition

Answer 20

The struggle for the utilization of resources such as food,light,water,mating,space,oxygen or carbon dioxide etc by different members of a different species that are living together in a community

Question 21

Mention some factors which are competition for living organisms

Answer 21

Space
food
mate

Question 22

What do we mean by competition for space?

Answer 22

Animals compete for territory. If they are not successful they will find it much more difficult to attract a mate and cannot breed

Seedlings compete for space in order to germnate grow and photosynthesize,in order to + for light and water.

Question 23

What do we mean by competition for food?

Answer 23

Members of the same species and of a different species compete for food

ex: different species of birds compete for the same food

Question 24

What do we mean by competition of mate?

Answer 24

In many species the male competes for the female, therefore the best genes will be passed on.

Ex; birds will attract the females by showing off their colours or doing a courtship dance

Or some primates will try to attract females by holding an infant to give off the impression that they are good fathers

Question 25

Define parasitism

Answer 25

It occurs when one species lives in or on another organism. This is the host. The parasite often harms and weakens the host,whilst the parasite obtains food at the host’s expense.

Question 26

What are the 2 types of parasites?

Answer 26

Ectoparasites and endoparasites

Ectoparasites: attach themselves outside of the body’s host and many only form temporary associations. ex: ticks or fleas

Endoparasites: live inside the host’sbody and it becomes its habitat,giving it food,shelter and protection

ex: bacteria or viruses

Question 27

Define autotroph

Answer 27

Organisms which can synthesie their own food from inorganic molecules,like plants or bacteria. Halophytic /chemophytic

Question 28

Define heterotroph

Answer 28

Organisms which are dependant on obtaining organic food molecules from its environment or other autotrophs because its unable to synthesize its own food

Question 29

Define decomposers

Answer 29

Decomposers are living organisms like bacteria or fungi which obtain their nutrients by breaking down dead decaying organic matter. Therefore they are important in the break down of dead organisms,

Question 30

Define detritivores

Answer 30

Living organisms like bacteria which obtain their nutrients from small organic debris fragments which have been generally left by decomposers. Therefore detritivores help decomposers.

Question 31

Define predation

Answer 31

Predators are organisms which feed on prey

If the prey will decrease then predators will starve

If the predators decrease, then the prey increases

If prey increases, there will be more food for the predators

Even human impact influences the concentrations of prey and predators

Question 32

True or false

Predators increase if the conditions are favourable

Answer 32

True because they can breed in the optimum conditions

Question 33

What makes a good predator?

Answer 33

Some predators hunt in packs and then share the food. Some predators also target the young and this eliminates the weak organisms from the environment

Or migrating to areas where they prey is more plentiful

Question 34

How do prey try to escape their predators?

Answer 34

Camoflauge:by blendng in with their surroundings

Some prey mimic other animals

Some prey have warning colours

Some try to run,swim or fly faster than the predators,whilst other stay in groups

Question 35

Define symbiosis

Answer 35

Any type of ongoing persistent biological interaction between 2 organisms

For example: cellulose digesting bacteria in herbivores OR

nitrogen fixing bacteria with plants

Question 36

Define mutualism

Answer 36

When 2 organisms live in relation to each other and both gain from the relationship

Question 37

Define commensalism

Answer 37

An association between 2 organisms where one organism benefits whilst the other is not affected

Question 38

True or false

Energy does not get recycled, but inorganic nutrients like nitrogen and carbon dioxide do get recycled

Answer 38

true

Question 39

Why is only 10% of energy passed through one trophic level to another in food chains?

Answer 39

All energy initiially comes from sunlight,however energy in ecosystems in the end it gets lost as heat.Energy is never recycled because energy can not be created nor destroyed.

Energy gets released in diffrent forms

The other inorganic nutrients that autotrophs obtain from the soil or water THEY ARE passed through from one organism to another.

When animals die the decomposers will obtain their nutrients from the dead animals. However at this stage the the energy is lost as heat and the inorganic nutrientsare taken up by the soil or the water to be taken up again

Question 40

Continue to elaborate

Answer 40

Energy enters the ecosystem as light.

HOWEVER only 1% of this energy is used by the plant because some of the energy will be used for photosythesis,some energy will be lost by transpiration, some energy will be reflected back by the leaf (lost),and the rest is lost as heat. (Gross primary production)

Therefore 90% of the energy is lost. Furthermore,10% of the energy will be passed on from the plants to the primary consumer

Therefore at each trophic level energy is lost mostly due to heat but other factpors include egestion,excrtion,growth or movement or inedible food

Then all the organisms die and will be used as food fro the decomposers. Then the last of the eenrgy is extracted and lost as heat.

Question 41

When does the greatest loss of energy happen and where does the greatest gain of energy happen/more efficient?

Answer 41

More efficient: from the primary consumer to the secodary consumer because a large ammount of flesh is digested and absorbed

Loss: from the producer to the consumer

Much of the energy is obtained from plants, because when it comes to the animals the energy is lost from each tropic level.

Question 42

What is a pyramid of energy?

Answer 42

A pyramid of energy represents the flow of energy through each trophic level in an ecosystem through a fixed period of time

Question 43

Explain the structure of a pyramid of energy

Answer 43

In order for the ecosystem to sustain itself and remain healthy, the lower trophic level must contain a higher amount of energy than there is at higher trophic levels. This allows for organisms on the lower trophic levels to not only maintain a stable population but to also transfer energy up the pyramid.

Question 44

Why are the natural cycles important?

Answer 44

Because in natural cycles resources are being used and replenished continuously

Question 45

What are the 4 steps of the nitrogen cycle?

Answer 45

Nitrogen fixation
Decay
nitrification
denitrification

Question 46

Explain the nitrogen cycle and draw a diagram

Answer 46

Nitrogen is very important for all living organisms. Regarding plants, they cannot make use of atmospheric nitrogen and needs to be changed into a usable form taken up by plants. In order to produce nitrates,urea and ammonia.

Nitrogen fixation can occur by 3 processes

Lightning: the enormous amount of energy which is found in lightning can break up nitrogen into nitrogen molecules. This will cause the nitrogen molecules to react with oxygen in the atmosphere to form oxides of nitrogen. These oxides of nitrogen will dissolve into the rainwater and will form nitrates . These nitrates will be carried into the soil and will be taken up by plants.

Nitrogen can also be fixed industrially: through a temperature of 600 degrees and with the use of a catalyst and with the use of hydrogen can be combined to form ammonia.. but most of it is further processed to form urea and ammonium nitrate

Nitrogen can also be fixed through nitrogen fixing bacteria. These types of bacteria can be found living directly in the soil or in the root nodules of leguminous plants. The nitrogen fixing bacteria will change nitrogen into ammonia, urea and uric acid.

After decay is going to occur. This is because the plants will take up the organic nitrogen compounds and these will be passed on to each trophic level . Now the nitrogen is going to leave and re-enter the ecosystem through the excretions of organisms. The decomposers are going to break down these excretions and will form ammonia which is going to re-enter back into the soil.

After the process of decay, the ammonia is going to get converted into nitrates/nitrites by the process of nitrification by nitrifying bacteria

After the process of nitrification, the nitrates will be converted back into atmospheric nitrogen by the process of denitrification by denitrifying bacteria completing the nitrogen cycle

Question 47

What is leaching?

Answer 47

When excess nitrates get into the soil,they can actually get lost due to excess water because they got disposed underneath the soil layers and this is not going to let the plants absorb the nutrients and will not allow the decomposers do their job. This can also occur due to excess fertilizers.

+ EUTROPHICATION

Question 48

What is the carbon cycle and draw a diagram

Answer 48

The first part of the carbon cycle is photosynthesis.

Plants will absorb atmospheric carbon dioxide from the atmosphere in order to carry out photosynthesis and convert carbon dioxide and water into sygar and oxygen. The carbon in the carbon dioxide is used to make su stances like cellulose, starch ,proteins and other pigments

The carbon dioxide is going to get released into the atmosphere agin by cellular respiration. Because plants will oxidize sugar in order to obtain energy and carbon dioxide is released as a waste product

Now eventually all plants and animals die. Decomposers will break down the remains of the dead animals and plants as a source of energy and will turn the carbon compounds into carbon dioxide

Regarding combustion : when carbon containing fossil fuels burn this actually increases the amount of carbon dioxide into the atmosphere. Fossil fuels are formed formed from ancient organisms that lived millions of years ago.

Therefore respiration and burning of fossil fuels increases the amount of carbon dioxide levels in the atmosphere

Question 49

Mention 2 ways how the carbon dioxide levels increase in the atmosphere in an anthropogenic way

Answer 49

Burning of fossil fuels
Deforestation

Question 50

Mention some other greenhouse gases

Answer 50

Methane
CFCs

These gases have a major depletion and negative effect on the ozone layer which is used to keep out harmful UV rays from the sun. If the ozone layer depletes, it can actually contribute to issues like skin cancer

Question 51

What are fossils?

Answer 51

Fossils are formed from the remains of dead plants and animals. Ad they are buried pressure and heat from the earth turn them into rock. The carbon from these organisms actually gets trapped and forms fossil fuels like natural gas, oil and coal. When these fossil fuels are burnt it contributes to increased levels of carbon dioxide into the atmosphere which affects the carbon cycle and causes climate change.