Ecology

Question 1

Define ecology

Answer 1

• study of interactions of organisms
• with one another
• with environment

Question 2

Abiotic environment

Answer 2

• physical factors

- light intensity, water availability, soil pH

Question 3

Biotic environment

Answer 3

• living things that organisms interact with
• populations in community live interdependently
• a change in one population would affect other populations
• includes decomposers e.g fungi, bacteria,

Question 4

Define habitat

Answer 4

• plc where organism live

- e.g. freshwater stream, forest, grassland, mangrove

Question 5

Define population

Answer 5

• grp of organisms of same species

- living tgt in particular habitat

Question 6

Define community

Answer 6

• populations of organisms living and interacting with each other
• particular habitat

Question 7

Define ecosystem

Answer 7

• community of organisms interacting with one another

- and abiotic environment

Question 8

Physical features of abiotic environment

Answer 8

1. Light intensity
2. Temperature
3. Water availability
4. Oxygen content
5. Salinity of soil, water
6. pH of soil, water

Question 9

How do physical features affect surrounding organisms

Answer 9

• growth of certain plants affects distribution of animals in location
• organisms found in region usually adapted to physical features of their environment

Question 10

Light intensity

Answer 10

• affects rate of photosynthesis, distribution and growth of plants and animals
• green plants only grow in adequate amt of sunlight
• animals depend directly or indirectly on distribution of plants

Question 11

Temperature

Answer 11

• affects rate of reaction of enzymes
• that control physiological and metabolic activities of organisms
• e.g. snakes hibernates in winter, less active as enzymatic rxn in body slower due to cold temp

Question 12

Water availability

Answer 12

• amt and pattern of rainfall
• air humidity
• water is main component of protoplasm
• in environment where water is scarce, organisms adapted for survival
• desert rat have longer loops of Henle for grate re absorption

Question 13

Oxygen

Answer 13

• needed for aerobic respiration to produce energy for cell activities
• e.g mangrove plant roots have pneumatophores to ensure they get enough oxygen
• breathing roots projected above mud surface
• pores for gaseous exchange

Question 14

Salinity

Answer 14

• refers to salt conc in water
• affects wp
• affects movement of salt and water in and out of cells or aquatic organisms

Question 15

pH

Answer 15

• acidity or alkalinity of a sln
• most organisms can only survive within a range of opt pH
• pH affects rate of enzyme reactions

Question 16

Producers

Answer 16

• anything that is able to convert carbon compounds to glucose
• contain chlorophyll, convert light to chemical energy
• all food chains start with producers
• green plants, photosynthetic bacteria

Question 17

Consumers

Answer 17

• unable to make food themselves
• obtain food and nutrients by feeding on other organisms
• primary, secondary, tertiary

Question 18

Decomposers

Answer 18

• obtain energy by breaking down dead organisms
• decomposition process releases inorganic nutrients (carbon and nitrogen) for nutrient cycling
• e.g. fungi, bacteria

Question 19

Food chain

Answer 19

• series of organisms
• energy transferred thru food
• illustrates feeding relationships btwn organisms

Question 20

Trophic lvl

Answer 20

• each stage in food chain/feeding position

Question 21

Food web

Answer 21

• consists of interlinked food chains

Question 22

Non-cyclic energy/ linear flow in ecosystem

Answer 22

1. Sun is main source of energy
2. Light energy converted to chemical energy by producers via photosynthesis
3. Energy from producers passed frm 1 trophic level to another thru feeding
4. flow of energy in ecosystem is non-cyclic, energy lost to environment as heat (respiration), doesnt return to same system
5. egested and excreted materials and dead organisms contain trapped energy

Question 23

Trapped energy in excreted and dead matter

Answer 23

• egested, excreted matter and dead organisms contain trapped chemical energy
• released thru decomposition
• decomposers use some of the trapped chemical energy for own needs
• rest is lost as energy

Question 24

Ecological pyramids

Answer 24

• Pyramid of numbers
• Pyramid of biomass
• Pyramid of energy
• used to compare trophic lvls of food chain

Question 25

Pyramid of numbers

Answer 25

• comparison of number of organisms present at each trophic lvl
• particular time

Question 26

Pyramid of biomass

Answer 26

• comparison of mass of organisms
• present at each trophic lvl at particular time
• dry mass
• mass of organism after all water removed
• e.g. dry organisms in an oven until a constant mass is obtained

Question 27

Inverted/oddly shaped pyramid of numbers

Answer 27

• on 1 trophic lvl are parasitic on organisms of another trophic level
• many small organisms feed on a large organism

Question 28

Inverted/oddly shaped pyramid of biomass

Answer 28

• organisms on 1 trophic lvl has high reproductive rate (e.g. phytoplankton, zoo plankton)
• based on standing mass, not taking into account reproductive rate

Question 29

Pyramid of energy

Answer 29

• total energy in each trophic lvl of food chain
• over certain period of time
• broad at base, narrow at top
• energy lost going down food chain

Question 30

How is energy lost to environment

Answer 30

• food transfer
• heat during respiration
• uneaten body parts
• undigested matter egested by consumers
• waste products excreted by consumers

Question 31

Nutrient cycling

Answer 31

• balanced ecosystem
• nutrients not lost, continually recycled
• cycling of nutrients brought abt by physical, chemical and biological processes
• e.g. carbon

Question 32

Carbon cycle

Answer 32

• carbon constantly removed frm and released into atmosphere in the form of CO2
• conc of CO2 fairly constant (in environment)

Question 33

Importance of carbon cycle

Answer 33

1. Ensures continuous supply of carbon dioxide for photosynthesis
2. Enables energy to flow thru the ecosystem
   - carbon compounds carry trapped solar energy from one organism to another

Question 34

Carbon cycle pathway (How CO2 is removed)

Answer 34

• removed from environment via photosynthesis
• passed on via feeding (carbon compounds becomes part of consumer’s body)
• fossil fuel (carbon compounds preserved as fossil fuels)

Question 35

Carbon cycle pathway (How CO2 released)

Answer 35

1. Respiration
   - carbon compounds broken down into carbon dioxide
2. Combustion
   - complete combustion fossil fuels release CO2
3. Decomposition
   - organisms die, dead matter broken down into simple substances like CO2 by decomposers

Question 36

Define carbon sink

Answer 36

• area that stores carbon compounds for an indefinite period
• stores more carbon than releases
• e.g. oceans, forests

Question 37

Ocean (carbon sink)

Answer 37

• one of largests on earth
• CO2 dissolves in water absorbed and used by phytoplankton and algae (photosynthesis)
• portion of carbon compounds buried in seabed (fossil fuels e.g. natural gas, oil)
• adding iron compounds (ie. iron oxide/sulphate) increases photosynthesis activity

Question 38

Forest (carbon sink)

Answer 38

• atmospheric CO2 absorbed by plants, used in photosynthesis
• large amt of carbon compounds stored in trees
• remains of dead trees form coal (fossil fuel)