BIOS 110 Exam 1 Key Concepts

What are the two hypotheses of spontaneous generation? How did life originate?

Theorized in 1590 that life generated spontaneously from non-living things and originated in multiple places. Today, we know that cells do not arise from non-living things (originated once, 3.6B years ago) and now all cells arise from preexisting cells.

What are the 5 characteristics of life?

1. Made of membrane-bound cells. All cells arise from preexisting cells

2. Life requires energy (chemical energy stored in bonds). After death, chemical bonds break through decomposition and energy is released.

3. Capable of reproduction.

4. Has genetic information (Hereditary information is passed down through chromosomes)

5. Life evolves (leading to advantageous traits)

What is the theory of evolution by natural selection?

States that all species evolved from preexisting species (originated from one species). Looking at shared DNA, we know which organisms are closely related.

What is ecology?

Ecology is the study of organisms’ abundance, distribution, and interactions with biotic and abiotic environment.

What are some biotic factors?

Herbivores, predators, plants, decomposers

What are some abiotic factors?

Climate, soil, water, sunlight

What do ecologists study? What are the five types?

Ecologists work at one or more levels to understand organisms’ distribution, abundance, and how they interact with their physical and biological surroundings. The five types are population, organismal, community, global, and ecosystem ecologists.

What is a population? What does an population ecologist study?

A population is a group of interbreeding individuals at a defined time and place. A population ecologist studies how populations increase, decrease, or remain stable. (No behavior, just population size)

What does a community ecologist study?

A community ecologist studies how different species interact with eachother, a complex network of relationships. They study competition, predation, mutualism, parasitism, commensalism, and food webs.

What does an organismal ecologist study?

An organismal ecologist studies behavior, such as how organisms find food, avoid predators, or attract mates.

What does a global ecologist study?

A global ecologist studies the global biosphere (the layer on Earth where all life exists), including climate change and human impact on the environment.

What does an ecosystem ecologist study?

An ecosystem ecologist studies whole systems, including biotic and abiotic factors. They study the energy flow and nutrient cycle.

What are the 4 factors that determine distribution and abundance?

1. Abiotic factors

2. Biotic factors

3. History and dispersal (continents shifting, disease)

4. Human influence (hunting, farming, invasive species, introduced species)

What is the difference between weather and climate?

Weather is the atmospheric environmental conditions (temperature, rainfall, sunlight) at a defined time and place.

Climate is the long-term average weather at a given place.

Why are the tropics hot and the poles are cold?

The tripics are hot due to the angle of sunlight and amount of sunlight per surface area.

At the equator, sunlight shines directly overhead and is concentrated on a small area. At the poles, sunlight shines at a small angle and is spread out on a larger area.

Why are the tropics wet?

The tropics are wet because of Hadley cells. Warm air moves to the equator and rises, dropping rain. Dry cold air is then pushed poleward, descends, and absorbs moisture.

What are the 4 biome types? (explain their location, precipitation, temperature)

1. Tropical rainforests (equator). Intense competition for light, many layers (3D), highly productive, extremely diverse. BUT nutrient-poor because competition is fierce.

2. Subtropical deserts (30 N/S of equator). Hot, humid, rarely rains. Species have adapted to dry climates.

3. Boreal forests (moderately close to North pole). Have many conifer trees, low temperature, low precipitation, low species diversity.

4. Arctic tundras (close to North pole). Have tree-less landscape, low productivity, low species diversity.

What is the Coriollis effect?

The rotation of Earth creates wind currents called trade winds (east to west OR west to east). These winds also carry millions of tons of dust from Sahara desert, carrying nutrients.

What are the two factors that cause seasonality?

1. Earth’s elliptical orbit (allows different parts of the world to have more sunlight during seasons)

2. Earth’s tilt (23.5 degree tilt allows poles to receive more sunlight in summer)

What 3 factors determine global climate?

1. Earth’s shape (spherical shape distributes sun’s energy unevenly. varying angles of sunlight)

2. Earth’s revolution around the sun on a tilted axis (seasonality)

3. Earth’s rotation on its axis (leads to Corriolid effect)

How do mountains affect the climate?

Hot air rises on one side of the mountain, cannot travel to the opposite side, then cools and rains over the mountain. This causes the opposite side to be much drier.

How do gyres affect ocean temperatures?

Gyres (massive ocean currents cycles) bring warm water to colder latitudes (in the direction of Corriolis effect). For example, Europe is warmer than Canada despite being at the same latitude because of the North Atlantic Gyre, pushing warm water from North America to Europe.

What are the five properties of population?

1. Population size

2. Density

3. Dispersion

4. Variability

5. Age structure

What is population size?

The number of individuals of a species at a given time. Also known as abundance.

What is density?

The number of individuals per unit area or volume. Density affects resource consumption and competition more than size.

What are the three types of dispersion?

1. Clumping (due to more suitable habitats, safety in herds, plant germination close to parent)

2. Random spacing (no pattern)

3. Uniform (due to strong interactions among individuals, such as water competition or territory, which causes individuals to be spaced apart from each other.)

What is variability?

The natural differences among individuals in a population, including behavior and physical attributes.

What is age structure? (age pyramid)

Describes the number of individuals in each age group of a population.

Some developed countries (Japan) → top-heavy, decline in growth

Developed countries → uniform, slow growth

Developing countries → bottom-heavy, rapid growth

What are the two types of population growth?

dN/dT = Births + Immigration - Deaths - Emigration

1. Continuous (humans) and discrete (all other species, seasonal) exponential population growth

2. Logistic population growth (K, carrying capacity)

What is the formula and graph for continuous exponential growth?

dN/dT = rN. J-shaped graph.

What is the formula and graph for discrete exponential growth? (seasonal)

Nt = N0 + lambda^t OR lambda = e^rt. to solve, move to ln(lambda) = rt and solve for r, per capita.

What is the formula and graph for logistic growth (has K, carrying capacity)

dT/dN = rN [(K-N/)K]

What does r indicate? r_max?

r is the per capita growth. r_max is the per capita growth under optimal conditions (impossible to achieve).

r < r_max

r = 0 indicates population is constant

r > 0 indicates the population increases

r < 0 indicates the population decreases

How are some populations cyclic?

The population of one species increases while the other decreases, then after a few years, the opposite occurs and this continuously occurs multiple times. There are two hypothesesis:
1. Top-heavy hypothesis where the population chanages depending on the predator

2. Bottom-heavy hypothesis where the populations change depenidng on the prey

What are density-dependent factors in population growth?

Factors that limit logistic growth (has K, carrying capacity). Biotic factors such as competition, predation, disease, that affect a population’s growth.

What are density-independent factors in population growth?

Environmental factors independent of density that limit population growth, such as natural disasters including wildfires, floods, volcanos, droughts.