HESI Science (Biology): Ecology, Taxonomy, Evolution, and Bio Basics

Taxonomy

classification of living organisms into different groupings at different levels based on similar characteristics and DNA

Scientific Method steps:

1. Identifying a problem or posing a question

2. Formulating a hypothesis or an educated guess

3. Conducting experiments or tests that will provide a basis to solve the problem or answer the question

4. Observing the results of the test

5. Drawing conclusions

Recursive Process

Means that as hypotheses are tested and more is learned, the questions should continue to change to reflect the changing body of knowledge

Animal Classified

Domain, Kingdom, Phylum, Class, Order, Family Genus, Species.

What does Kingdom level of classification include?

contains all living things that are animals (animals are multicellular, cannot produce their own food, and are motile).

What does Phylum level of classification include?

The phylum Chordata is now more limited, as it only contains animals that have a backbone

animals such as insects and jellyfish lack backbones and would be placed into a different phylum.

What does Order level of classification include?

Order Carnivora (meat eaters) contains the carnivores dogs and wolves. The order Rodentia contains rodents like mice. Once we get to the genus and species level, we are looking at the scientific name of the organism.

What is Evolution?

Describes the changes in traits (alleles) in a population over time.

What is Natural Selection?

Dictating which individuals in a population will be more likely to survive and reproduce. The driving force behind the change of an organism’s population due to environmental factors.

What is Directional Selection?

As this type of natural selection favors one trait vs the other, it pushes the population to have more of a single trait.

What is Disruptive Selection?

The environment is more favorable to the extremes in a phenotype or trait and selects against the average or intermediate trait.

Disruptive selection would involve multiple alleles for a trait, such as dark mice, brown mice, and white mice.

What is Stabilizing Selection?

The environment favors a more average or intermediate phenotype. In this case, the extremes in phenotypes are not favored.

What is Convergent Evolution?

Happens when two or more unrelated organisms evolve to have similar traits or features based on their environment.

Ex. Sharks and Dolphins:

Sharks are a type of fish, and dolphins are a type of mammal. They are not closely related. They are both ocean predators, and they have a similar body type (torpedo-shaped).

What is Divergent Evolution?

Occurs when variations in a trait among closely related organisms results in the creation of a different species.

Ex: Foxes and Dogs

They both share a canine common ancestor (wolf).

What is an Ecosystem?

An ecosystem includes all living organisms and their physical non-living habitat

What are Biotic Factors?

Are the living organisms such as plants, insects, and animals that interact with each other.

What are Abiotic Factors

Are the non-living factors such as air, water, soil and rocks that impact habitat. 

What is an Exponential Growth Curve (also known as J-Curve)?

A J-curve is due to rapid growth when resources are unlimited. Once the resources become more limited, the population growth rate will slow down to zero (the number of births would equal the number of deaths).

What is an Logistic Growth Curve (also known as S-Curve)?

Leads to a more stable population (in terms of numbers) and also results from when resources are limited. 

What is an R-Curve?

Population has high rates of change due to high number of offspring, but low survivorship

What is K-curve?

Population growth rate is stable due to low number of offspring and high survivorship 

What does the food chain consist of?

The producers, primary consumers, secondary and tertiary consumers.

What are Producers?

Are plants and other organisms that can perform photosynthesis, converting sun energy into chemical energy (carbohydrates). 

Producers provide food for primary consumers

What are Primary consumers

Herbivores. Primary consumers are now food for secondary consumers

What are Secondary Consumers?

Carnivores, and they are become food for the tertiary consumers

What are Tertitary Consumers?

“Top Carnivores”. Who are at the top of the food chain.

What are

What are Detritivores?

Known as decomposers, eat dead and decaying organisms.

Ex: of detritivores are bacteria and fungi. 

What is symbiosis

When organisms form a relationship by living together

What are the 3 types of Symbiotic Relationships?

mutualism, commensalism, and parasitism

What happens to organisms during Mutualism?

Both organisms benefit, such as in the honey bee and flowering plants relationship.

What happens to organisms during Commensalism?

Only one organism benefits from the relationship, while the other organism is not harmed.

Ex: Barnacles and whales. The barnacles do not harm the whale and the whale does not get any benefit from the barnacles attached to them. The barnacles, however, get a free ride and free access to plenty of food (remainders of whatever the whale ate).

What happens to organisms during Parasitism?

Only one member of the relationship benefits, while the other organism is harmed.

A good example of parasitism is when a tick attaches to a cat. The tick sucks blood from the cat and causes skin irritation.

What is Predation?

Is categorized as one organism eating another organism and is not categorized as a symbiotic relationship. (NOT categorized as a Symbiotic Relationship)

What are the characteristics of a Tropical Rainforest Biome?

• Average temperatures are high

• Abundant rainfall

• Tall trees with dense vegetation

What are the characteristics of a Temperate (Deciduous) Forest Biome?

• Moderate temperature with some freezing

• Adequate rainfall

• Deciduous trees that lose their leaves in fall

What are the characteristics of a Boreal (Coniferous) Forest Biome?

• Average temperatures are cold

• Adequate rainfall

• Evergreen coniferous trees that have needles and do not shed needles in fall

What are the characteristics of a Savanna Biome?

• Tropical temperatures

• Low rainfall

• Mostly grass with few individual trees scattered throughout

What are the characteristics of a Desert Biome?

• Average temperatures can be high or low

• Low rainfall

• Plants typically covered with spines

What are the characteristics of a Grassland Biome?

• Moderate temperature with some freezing

• Adequate rainfall

• Mostly grass with little trees

What are the characteristics of a Tundra Biome?

• Average temperature very low

• Moderate rainfall

• Plants are short and low to ground

What is Succession?

When a habitat is barren or is destroyed by outside forces (such as a fire) it will become inhabited overtime

What is Primary Succession?

starts from barren, never inhabited land.

What is Secondary Succession?

Occurs after a disturbance, such as fire or deforestation

What are Pioneer Species.

The first step of Biological Succession, pioneer species do not require much to grow, and help to make the environment more suitable for other species of organisms to populate the area.

What is Intermediate Species?

The second step of Biological Succession, which include grasses and shrubs that will start to populate the area.

What is Climax Community?

The last stage in biological succession, and is reached when the habitat is stabilized by the presence of other trees, plants, and animals.