unit 4: ecology

Question 1

ecology

Answer 1

the study of relationships between living organisms and between organisms and their environment.

Question 2

species

Answer 2

groups of organisms that can potentially interbreed to produce fertile offspring

Question 3

hybrid

Answer 3

offspring of two different species

Question 4

population

Answer 4

a group of organisms of the same species who live in the same area at the same time

Question 5

communities

Answer 5

a group of populations living and interacting with each other in an area

Question 6

ecosystem

Answer 6

the community of organisms in an area and its interactions with the abiotic factors of the environment

Question 7

abiotic factors

Answer 7

• non-living
• hydrosphere, atmosphere, lithosphere
• ex) light, heat, minerals, oxygen, humidity

Question 8

biotic factors

Answer 8

• living
• biosphere
• ex) plants, fungi, protists, animals, bacteria

Question 9

autotrophs

Answer 9

• self-feeding
• they make their own organic molecules from carbon dioxide substances, such as inorganic substances
• involves photosynthesis:
• take light energy and inorganic substances to obtain chemical energy in the form of organic compounds
• ex) plants, algae, bacteria

Question 10

heterotrophs

Answer 10

• feed on others
  -must obtain organic molecules from other organisms
• get their chemical energy from autotrophs or other heterotrophs
• detritvores (ingest organic matter that is living or has been killed)
• ex) dogs, fungi, yeast, humans

Question 11

heterotrophs: consumers, detritivores, and saprotrophs

Answer 11

consumers:
- heterotrophs that feed on living things by ingestion
- ex) bear
detritivores:
- heterotrophs that obtain organic nutrients from detritus by internal digestion
- eat dead leaves, feces or carcasses
- ex) worms, beetles, woodlice
saprotrophs:
- heterotrophs that obtain organic nutrients from dead organic matter by external digestion
- ex) fungi, bacteria

Question 12

food chain

Answer 12

a sequence showing the feeding relationships and energy flow between species

Question 13

food web

Answer 13

a system of interlocking and interdependent food chains

Question 14

trophic levels

Answer 14

• refer to an organisms position in the food chain
• help classify organisms by their feeding relationships with other organisms of the same ecosystem
• bottom to top
• producers, primary consumer, secondary consumer, tertiary consumer, quaternary consumer
• in order for food chains to work, there must be a large number of producers and fewer members of each subsequent trophic level

Question 15

energy in ecosystems

Answer 15

• most ecosystems rely on a supply of energy from light energy
• producers such as plants, algae, and cyanobacteria, harness light energy through photosynthesis.
• producers are the most important organisms in any food chain
• without them, the next trophic level would have nothing to eat
  (not only do they supply energy, but also intake carbon)

Question 16

energy conversions

Answer 16

• light energy is converted to chemical energy in carbon compounds by photosynthesis.
• once light energy has been absorbed by the producers, the light energy obtained by photosynthesis is available to the next trophic level
• energy is transferred from one organism to the next when carbs, lipids, or proteins are digested (grass eaten by a cow—> chemical energy transferred to cow
• chemical energy in carbon compounds flows through food by means of feeding
• energy is passed from producers to consumers
• producers use some energy by cell respiration
• energy released in this way is lost to the environment as waste heat

Question 17

energy loss

Answer 17

• only transferred energy can be used by the next trophic level
• only a small amount of energy which an organism absorbs is converted into chemical energy
• usually only about 10-70% of the energy is used from the previous steps in the food chain

Question 18

living organisms can convert energy in these ways

Answer 18

• chemical to kinetic (muscle contractions)
• chemical to electrical (nerve cells)
• chemical to heat (cell respiration, making ATP)
• synthesizing large molecules
• active transport of molecules
• muscle contraction
• heat-generating adipose tissue
• energy from these processes is eventually converted into heat
• living organisms cannot convert heat into other forms energy

Question 19

why not all energy is used

Answer 19

• most energy is lost as heat due to cell respiration at all trophic levels
• some organisms die before being eaten by an organism from the next trophic level
• someparts of an organism