4.1 Species and ecosystems

Question 1

Define species

Answer 1

SPECIES: roup of organisms that can potentially interbreed to produce fertile, viable offspring

Question 2

Define population

Answer 2

POPULATION: a group of organisms of the same species that are living in the same area at the same time

Question 3

Grouping individuals in ecosystems

Answer 3

Species -> population -> community -> ecosystem (community + habitat+ abiotic environment)

Popualtion - same species

Community - different species

Question 4

How are organisms goruped by the way they obtain energy?

Answer 4

Producers - autotrophs: produce own organic substances, E from sunlight

Consumers - heterotrophs: organic substances form other organisms

Heteroptrophs: consumers, detritivores (ingest non living matter), saprothrophs (external digestion - decomposers)

Question 5

Types of autotrophs

Answer 5

Phototrophs: sunlight

Chemiotrophs: oxidation of inorganic subtsances

Question 6

What are the types of consumers?

Answer 6

Consumers: herbivores (plant matter), carnivores (animal meat), omnivores (both plants and meat), scavenegers (feed on dead meat, ex hyena, crow)

Question 8

Explain detritivores

Answer 8

• obtain nutrients from non-living organic sources (detritus and humus - decaying leaf matter)
• examples: earthworms, snails

Question 9

Explain saprotrophs

Answer 9

• live on / in non-living organic matter, _secrete digestive enzyme_s into it (external digestion) and absorbing the products of digestion
• complete break down of dead matter - decomposers
• example: bacteria, fungi

Question 10

Explain nutrient recycling

Answer 10

• nutrients (material required by an organism) are finite -> need to be recycled
• autotrophs obtain inorganic nutrients -> convert them into organic compounds
• heterotrophs ingest organic compounds -> use them for growth / respiration -> releasing inorganic byproducts
• organisms die, saprotrophs decompose the remains -> free inorganic materials into the soil
• return of inorganic nutrients to the soil ensures the continual supply of raw materials for the autotrophs

Question 11

What are the features of sustainble ecosystems?

Answer 11

• Energy availability – light from the sun provides the initial energy source for almost all communities
• Nutrient availability – saprotrophic decomposers ensure the constant recycling of inorganic nutrients within an environment
• Recycling of wastes – certain bacteria can detoxify harmful waste byproducts (e.g. Nitrosomonas bacteria)

Question 12

Define mesocosm

Answer 12

MESOCOSM: enclosed environments that allow a small part of a natural environment to be observed under controlled conditions

Question 13

What does chi-squared test provide?

Answer 13

Tells how likely it is that the obtained variation is due to chance - how well the observed variation resembles the expected

Question 14

Explain quadrant sampling

Answer 14

Tests the presence of two species within a g_iven environment_ can be determined using quadrat sampling