IB Ecology

Q: What is a species in ecology?

A group of organisms that can interbreed and produce fertile offspring.

Q: Define population in an ecological context.

The total number of individuals of a particular species in a given area.

Q: What constitutes a community in ecology?

A group of populations of different species living and interacting in the same area.

Q: Define habitat.

The environment where a species usually lives.

Q: What is an ecosystem?

A community of living organisms interacting with their abiotic (non-living) environment.

Q: Define ecology.

The study of living organisms and their interactions with the environment.

Q: What is an autotroph?

An organism that makes its own energy from inorganic molecules.

Q: Differentiate between photoautotrophs and chemoautotrophs.

Photoautotrophs use light from the sun to make energy and store it as carbon compounds, while chemoautotrophs oxidize inorganic molecules (e.g., in deep hydrothermal vents) to obtain energy.

Q: What is a heterotroph?

An organism that obtains energy by consuming other organic matter.

Q: Define saprotrophs.

Organisms that obtain energy by secreting enzymes onto detritus and absorbing the products of digestion.

Q: What distinguishes parasites from other heterotrophs?

Parasites obtain organic molecules from a host organism without killing it but weaken the host.

Q: Define holozoic nutrition.

A mode of nutrition where organisms feed on other organisms that are dead or alive.

Q: What is ingestion in the context of nutrition?

The intake of food into the organism's body.

Q: Describe digestion.

The breakdown of food into smaller, soluble molecules.

Q: What occurs during absorption?

Small, soluble molecules from digested food are absorbed into the bloodstream.

Q: Define egestion.

The removal of unused food from the body as waste.

Q: Define the term "autotroph" and give two examples of autotrophic organisms.

An autotroph is an organism that makes its own energy from inorganic molecules. Examples include green plants (photoautotrophs) and certain bacteria (chemoautotrophs).

Q: Explain the difference between photoautotrophs and chemoautotrophs in terms of their energy sources.

Photoautotrophs use sunlight as their energy source, while chemoautotrophs obtain energy by oxidizing inorganic molecules.

Q: What is the role of saprotrophs in an ecosystem? Provide an example of a saprotrophic organism.

Saprotrophs decompose dead organic matter, recycling nutrients back into the ecosystem. An example is the common mushroom.

Q: Describe the process of ingestion and how it differs from egestion.

Ingestion is the intake of food into the body, whereas egestion is the expulsion of undigested food as waste.

Q: Differentiate between a parasite and a saprotroph in terms of their nutritional strategies.

Parasites obtain nutrients from a living host without killing it, while saprotrophs decompose dead organic matter.

Q: Describe the modes of nutrition found in different species and how these modes affect their ecological roles.

Autotrophs produce their own energy, forming the base of food webs. Heterotrophs consume other organisms, transferring energy through trophic levels. Saprotrophs decompose dead matter, recycling nutrients.

Q: What is an obligate aerobe?

An organism that requires oxygen for survival.

Q: Example of an obligate aerobe.

Most animals and plants.

Q: Define an obligate anaerobe.

An organism that can only survive without oxygen.

Q: Example of an obligate anaerobe.

Certain bacteria found in deep sediments.

Q: What is a facultative anaerobe?

An organism that can survive with or without oxygen.

Q: Example of a facultative anaerobe.

Gut bacteria.

Q: What is a niche in ecology?

A habitat that provides the necessary environmental factors for the coexistence of many species.

Q: List the key components of a niche’s role in the environment.

Physical and environmental conditions, interactions with other species, and the activity pattern of the organism.

Q: Define mutualism.

An interaction where two or more organisms work together for mutual benefit.

Q: Provide an example of mutualism involving gut bacteria in humans.

Humans provide nutrients and safety to the bacteria, while bacteria help digest food for humans.

Q: What is a realised niche?

The actual environment in which an organism lives, often smaller due to factors like competition.

Q: Define fundamental niche.

The theoretical environment where an organism can live without restrictions.

Q: How do organisms fit into a niche?

By adapting to live in specific niche conditions, such as herbivores developing specialized teeth for breaking down cellulose.

Q: Define "obligate aerobe" and provide an example of an organism that fits this classification.

An obligate aerobe requires oxygen for survival. An example is most animals.

Q: What is the difference between a fundamental niche and a realised niche?

A fundamental niche is the potential habitat of an organism without competition, while a realised niche is the actual habitat where it lives due to environmental limitations and competition.

Q: Explain the concept of mutualism and provide another example besides gut bacteria in humans.

Mutualism is a beneficial interaction between two species. An example is the relationship between bees and flowering plants, where bees get nectar and plants get pollinated.

Q: Describe the adaptations that herbivores might have for feeding on plants.

Herbivores may have specialized teeth for grinding cellulose, elongated digestive tracts for fermenting plant material, and enzymes to break down cellulose.

Q: What are the three types of bacteria based on their oxygen requirements? Provide an example of each.

Obligate aerobes (e.g., most plants), obligate anaerobes (e.g., certain gut bacteria), and facultative anaerobes (e.g., E. coli).

Q: Explain the role of competition in shaping the realised niches of two or more species.

Competition for resources can limit the available habitat for species, causing them to occupy smaller or different realised niches to reduce overlap.

Q: What is an open system in ecology?

A system where both energy and mass can move in and out.

Q: Example of an open system.

Ecosystems.

Q: Define a closed system.

A system where energy moves in and out, but mass does not transfer.

Q: What characte