Concepts of Biology Flashcards

Flashcards about Evolution and its Processes, Population and Community Ecology, Ecosystems and the Biosphere, and Conservation and Biodiversity.

Charles Darwin

The first scientist to study Biological Evolution and defined evolution as descent with modification.

Descent with modification (Evolution)

A change in the genetic characteristics (DNA) of a population of organisms over time, allowing organisms to adapt better to their environment and pass modified genes to offspring.

Natural Selection and Genetic Drift

Evolution occurs through these two major ways.

Natural Selection

Organisms with current favorable traits have a better chance at survival, leading to more reproductive opportunities and offspring with the same favorable traits.

Genetic Drift

Differences between organisms in reproduction or survival due to chance; random environmental disturbances can cause this.

Adaptation

A change in characteristic/trait that improves the survival of an organism. It is a result of natural selection.

Diversity

A result of speciation where different species cannot crossbreed.

Species

An organism that cannot reproduce with other species.

Homologous structures

Characteristics that arise due to a common ancestry; structures that are similar but have different function.

Vestigial structures

Structures in some organisms that seem to serve no useful function, suggesting ancestors had those features.

Artificial selection

Selecting best quality and eliminating weak ones in farming and domesticated animals.

Species

The building block units of population; a group of interbreeding population that does not crossbreed with other groups.

Natural Selection

The process in nature by which only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics.

Species

A group of interbreeding organisms with the same characteristics.

Population

Group of individuals of the same species.

Population size

Total number of individuals in a population.

Population density

Number of individuals per unit area.

Community

Made out of several populations.

Measuring changes in population size

Increasing factors include birth and immigration while decreasing factors include death and emigration.

Exponential Growth

J curve, indicates fast growth rate. When a population increases by a constant proportion from one generation to the next.

Doubling time

Measures how fast the population is growing; the shorter the time, the faster the population is growing.

Age structure (Pyramid)

The proportion of individuals in different countries, helps predicting the population growth rate.

Zero population growth

A condition in which a population neither grows nor declines, because the number of births in a year equals the number of deaths.

Limits to Population Growth

Environmental factors, such as food, habitat, and limited resources, that limit population growth.

Limits forcing populations

Populations demonstrate an S-shaped curve (logistic curve).

Carrying Capacity

The maximum number of individuals supported in an environment without depleting the resources.

Biotic potential

Population ability to reproduce. Increase growth rate(early puberty/longevity). Intrinsic.

Environmental Resistance: Density– dependant factors

Extrinsic, e.g. competition for food/predation/disease/jobs… Forces fast growing populations (J curve) to grow slower (S shape curve)

Density-independent factors

Natural disasters, weather fluctuations, fire and floods, pesticide use unrelated to population size. Cause sudden drop in population size.

Human Population Growth

Currently, humans demonstrate exponential population growth.

Ecosystem study

Interactions among living organisms and between living organisms and environment.

Community

Populations of two or more different species occupying the same geographical area.

Diversity

Measured in two ways: Number of species present and Abundance of these species.

Competition

When population of two or more species in a community rely on similar limiting resources (food, nesting sites…).

Predation

Consumer = predator, Food species = prey

Symbiotic relationship

Interaction in which one species (the SYMBIONT), lives in or on another species (the HOST).

Parasitism

One organism benefits and the other is harmed

Mutualism

Both organisms (Parasite and host) benefit

Commensalism

One organism is benefited and the other not affected

Food Webs

Shows who eats who, contain many food chains.

Producers

Plants/autotrophs at base of food chain

Heterotroph

Organism that cannot synthesize its own food and is dependent on complex organic substances for nutrition.

Carnivores

Meat eaters.

Omnivores

Eat plants and meat.

Biological magnification

Contaminant concentration increases progressively as we move up the food chain; substance is very slowly metabolized or excreted.

Keystone Species

Stabilizes community by having a tremendous effect on this community; if removed, entire community balance changes.

Pisaster as a Keystone Species

The presence of keystone species (sea star) help maintain species diversity.

Primary succession

Development of a new habitat (no soil).

Secondary succession

Recovering from a disturbance (soil). Community rebuilt.

Ecosystem

Area where we have two components living and non-living.

Ecosystem

Community of different organisms and with the physical environment.

Movement of energy

Escapes.

Nutrients/materials

Recycle.

How Ecosystems Work

Energy flow is a one- way path. Nutrients/materials recycled by decomposers.

Energy Capture

All living systems depend on adequate supply of energy and materials to support sustaining.

Decomposers

Recycled material including bacteria and fungi.

NPP= Net Primary Productivity

The amount of energy which primary producers can pass on to the secondary trophic level.

Energy

Flows (passes) through food chain.

Trophic level

Organism position in food chain.

Five major atmospheric cycles

Carbon, Hydrogen, Oxygen, Nitrogen, and Sulfur.

Fast Carbon Cycle

Plants, CO2 from air, photosynthesis: heterotrophs consume plants, cell respiration, CO2 release.

Slow Carbon Cycle

Plants and animals, die, oil fields, burn, CO2 back to ecosystem. Takes thousands of years.

Sulfur dioxide (SO2)

Released during burning of fossil fuels/gas. Has an international impact

Atmospheric carbon dioxide (CO2)

Important for photosynthesis and Contributes to global warming.

Biological Effects

Plant growth increases photosynthesis and water use.

Global Warming

When earth heats up-> temp. rises up. This happens when greenhouse gases trap heat and light from the sun in earth’s atmosphere->increases temp.

Impact on the carbon cycle (Industrial Revolution)

Due to burning of fossil fuels/coal/oil/natural gases carbon released in atmosphere increases carbon dioxide.

Deforestation:

Carbon dioxide increases as trees no longer absorbing carbon dioxide by photosynthesis.

Biological magnification

Contamination level increases as we move up in the food chain.