Biology Semester 1 Final Review 2025

Positive Feedback

A process in biology that amplifies a response or increase the output of a system.

Example of Positive Feedback

In child birth, the release of oxytocin increases contractions, which leads to more oxytocin being released.

Negative Feedback

A process in biology that counteracts a change, helping to maintain homeostasis.

Example of Negative Feedback

The regulation of body temperature in humans; when body temperature rises, mechanisms like sweating are activated to cool it down.

Excretory System

The system responsible for removing waste products from the body, primarily involving the kidneys.

Homeostasis

The process by which living organisms maintain a stable internal environment.

Nervous System

The system responsible for sending signals throughout the body, involving the spine, brain, and nerves.

Circulatory System

The system that pumps blood throughout the body to transport oxygen, consisting of the heart and arteries.

Mitosis

The process of cell division that results in two identical daughter cells, used for growth and repair.

Meiosis

The type of cell division that produces gametes, resulting in four genetically unique haploid cells.

Allele

Different versions of the same gene, influencing traits.

Phenotype

The physical expression of traits determined by an organism's genotype.

Genotype

The genetic makeup of an individual, represented by alleles.

Chromosome

A structure made of DNA that carries genetic information; humans have 23 pairs.

Gamete

A haploid reproductive cell (sperm or egg) that can unite with another to form a diploid organism.

Crossing Over

The exchange of genetic material between homologous chromosomes during meiosis, increasing genetic diversity.

Independent Assortment

The process during meiosis where different genes independently separate from one another when reproductive cells develop.

Invasive Species

A non-native species that spreads widely in a new ecosystem and causes harm to native species.

10% Rule

A guideline that states that only about 10% of the energy from one trophic level is available to the next level.

Trophic Pyramid

A graphical representation of the energy flow in an ecosystem, showing the levels of producers, consumers, and decomposers.

Cellular Respiration

The process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.

Photosynthesis

The process used by plants and some organisms to convert light energy into chemical energy in the form of glucose.

Biodiversity

The variety of life in the world or in a particular habitat or ecosystem.

Non-disjunction

An error in cell division that results in an unequal distribution of chromosomes.

Hybrid

An organism that has two different alleles for a trait.

Dominant Allele

An allele that expresses its trait even when paired with a recessive allele.

Recessive Allele

An allele that expresses its trait only when paired with an identical allele.

Carbon Dioxide

A colorless gas produced during cellular respiration and used during photosynthesis.

Glucose

A simple sugar that is an important energy source in living organisms and a product of photosynthesis.