Ecosystems and Biodiversity Quiz

Ecosystems

• Biodiversity is the variety of organisms in an ecosystem. An ecosystem combines the habitat and community. A habitat is the place where an organism lives, and the community consists of all the organisms present there.
• A population is a group of organisms of the same species. A species is a group of organisms that can interbreed to produce fertile offspring.
• An example of an ecosystem is a forest. A habitat within that ecosystem is a tree, while animals such as squirrels, deer and foxes make up its community. A population within that community includes foxes.
• A species example is deer, where offspring/young depicted in the image are fertile and can reproduce.
• A pitfall trap is a method to sample organisms in the soil. A hole is dug, a cup is placed at ground level, covered, so organisms fall in, and birds do not eat organisms. Setting several traps increases reliability, and checks allow organisms to not consume each other.

Distribution of Organisms

• Keys are used to identify organisms through branching keys and paired statements.
• Biotic factors (living factors) influence the distribution of living things. Examples of biotic factors in an ecosystem include predation (where predators eat prey), disease, and the availability of food.
• Grazing is relevant if factors are not too high or too low.
• Competition can be interspecific (between different species, like between foxes and owls) or intraspecific (between members of the same species, like two lions competing).

Quadrats

• Quadrats are used to sample plant abundance or amount. Randomly placing a quadrat, counting the number of squares with plants within that quadrat gives a representative result. Several quadrats improve reliability.

Abiotic Factors

• Abiotic factors (non-living factors) impact living thing distribution. Examples include light intensity, moisture content (measured by a moisture meter), pH (measured by a pH meter), temperature (measured by a thermometer).

A Line Transect

• A line transect is a method of studying organism distribution across a specific area, using measurements at different points along the line.

Photosynthesis

• Plants use photosynthesis, converting sunlight, water, and carbon dioxide into glucose and oxygen. Chlorophyll is the green pigment that absorbs sunlight.
• Photosynthesis happens in two stages: light-dependent reactions (splitting water into hydrogen and oxygen, converting light energy to chemical energy using ATP) and the Calvin cycle (using ATP and hydrogen with carbon dioxide to make glucose, a controlled reaction).
• Glucose can be used for energy in respiration, stored as starch, or built into cellulose.

Limiting factors

• Limiting factors of photosynthesis are light intensity, carbon dioxide concentration, and temperature. These factors control the rate of photosynthesis.

Energy in Ecosystems

• Producers (like plants) make their own food.
• Consumers eat other organisms.
• Herbivores eat plants.
• Carnivores eat animals.
• Omnivores eat both plant and animal matter

Food Chains/Webs

• A food chain shows who eats who, displaying the flow of energy. An arrow points from the food source to the organism that eats it.
• A food web shows multiple food chains.
• Energy is lost as heat and waste; only the energy used for growth is passed on.
• Pyramids of numbers and energy show the number of organisms and energy available at each level of the food chain respectively. These pyramids usually demonstrate a typical pyramid shape, but exceptions can exist where a tree is a food source, as seen in an example.

Food Production

• Increasing human population increases food requirements. Fertilizers and pesticides are used to increase crop yields, with advantages and disadvantages.

Nitrates and Pesticides

• Nitrates are needed to produce amino acids and proteins. Plants absorb nitrates from the soil; animals get nitrates by eating plants.
• Farmers use fertilizers to increase soil nitrates. Excessive fertilizer use can lead to algal blooms, oxygen depletion, and harm to aquatic life.
• Pesticides are used to kill pests. Pesticides enter the food chain through consumption and accumulate in higher trophic levels (bioaccumulation).

Evolution of Species

• Mutations are changes in genetic material (DNA). Mutations produce new alleles, the only source for new alleles (forms of a gene). Factors speeding up mutation rate include X-rays, UV radiation, gamma radiation, high temperature, and specific chemicals such as mustard gas.
• New alleles can enable adaptations to environmental changes, influencing population variations over time.

Natural Selection

• Natural selection, also called "survival of the fittest," occurs when there are challenges in an environment. The best-adapted organisms thrive, reproduce, and pass on traits, leading to population change.

Speciation

• Speciation is the formation of new species. It involves isolation, mutations, and natural selection within separated groups, leading to reproductive incompatibility and therefore a new species.