term 1 science

Allele

One of the two or more versions of a mutation at a certain location on a chromosome that is a variant form of a specific gene.

Microevolution

Mechanisms that alter the frequencies of alleles in gene pools within species over a shorter frame in comparison to macroevolution.

Hardy-Weinberg equilibrium

A state where allele frequencies remain constant; microevolution occurs if any criteria of this equilibrium are not fulfilled.

Mutations

A cause of variations resulting from viruses, erroneous replication, UV rays, or mutagenic chemicals that produce new alleles.

Genetic drift

Haphazard changes in the allele frequency in a population, typically observed in smaller populations.

Gene flow

The transfer of genes when alleles physically move between populations due to individual migration, increasing genetic diversity.

Natural selection

A process that can be artificial or natural, taking hundreds or thousands of years to cause remarkable changes based on the survival of individuals with best-suited characteristics.

Macroevolution

Evolutionary patterns observed above the species level on the tree of life at a grand scale across vast time periods.

Phyletic gradualism

A model proposing that most speciation events result from a gradual and uniform transformation of one species into a new one over vast amounts of time.

Anagenesis

The process of a gradual and uniform transformation of one species into a new one.

Punctuated equilibrium

A model proposing that grand patterns of change involve rapid splitting of species through cladogenesis followed by long periods of stasis.

Cladogenesis

The rapid splitting of one ancestral species into two or more descendant species.

Stasis

Long periods within the punctuated equilibrium model where descendant species undergo little to no evolutionary change.

Evolution

The change in characteristics of a species over several generations, relying on genetic variation and natural selection.

Phenotype

The physical characteristics of an organism that are affected by genetic variation.

Convergent evolution

The independent evolution of the same adaptations in different species under similar selection pressures, such as flight in insects, birds, and bats.

Adaptive radiation

When a species splits into a number of new forms due to environmental changes making new resources available or creating new challenges.

Homo sapiens

A culture-bearing upright-walking species that first evolved in Africa about $315,000$ years ago.

Hominini

The human tribe, comprising Homo sapiens and extinct predecessors like Ardipithecus and Australopithecus.

On the Origin of Species

The monumental book published by Charles Darwin in $1859$.

The Descent of Man

The book published by Charles Darwin in $1871$.

Node

A theoretical common ancestor representing a point for divergence into separate lineages rather than a 'missing link'.

Cell

The most basic unit of life, with the average adult having between $30 - 40 \text{ trillion}$ cells.

Tissue

A select group of cells with similar functions that come together.

Organism Organization

The structural hierarchy of the human body consisting of Cells \rightarrow Tissues \rightarrow Organs \rightarrow Organ System \rightarrow Organism.

Skeleton

The framework of the body composed of cartilage and bone, consisting of $300$ bones at birth and $206$ bones by adulthood.

Tendons

Specialised tissues that attach muscles to bones to assist in locomotion.

Cranial cavity

The space within the skull that protects the brain and other parts of the central nervous system.

Pleural cavity

The specific body cavity where the lungs are protected.

Abdominal cavity

The body cavity that houses the intestines, liver, and spleen.

Digestive system

The system responsible for breaking down food and assimilating nutrients for growth and cell repair.

Respiratory System

Also known as the ventilatory system or gas exchange system, it involves the intake of oxygen and the exhale of carbon dioxide.

Ovaries

Organs in the female reproductive system that produce ovum (female eggs) and the hormone estrogen.

Uterus

Also known as the womb, this is a pear-shaped organ where the fetus grows.

Human Physiology

The study of the physical, mechanical, and biochemical functions of humans.

Claude Bernard

Known as the father of Physiology and the father of modern experimental Physiology.

Human Anatomy

The study of the structure of an object and how human parts interact to form a functional unit.

Andreas Vesalius

The Belgian-born physician known as the father of human anatomy, famous for his work \"Fabrica\".

Gross anatomy

A type of anatomy that deals with structures that can be seen with the naked eyes.

Microscopic anatomy

A type of anatomy that deals with structures that can only be viewed under a microscope.

Cerebrum

The largest part of the brain, located in the forebrain, responsible for thinking, motor function, and understanding language.

Somatic nervous system

A part of the Peripheral Nervous System that transmits motor and sensory impulses between the CNS and the limbs or sensory organs.

Autonomic Nervous System

A system that relays impulses to smooth muscles and involuntary organs like the heart and lungs without conscious effort.

Gastric juice

A mixture of Hydrochloric acid and enzymes secreted by the stomach wall to breakdown food and kill bacteria.

Villi

Finger-like outgrowths in the small intestine with networks of blood vessels that absorb food.

Small intestine

A highly coiled organ approximately $7.5\,m$ in length that receives secretions from the liver and pancreas.

Large intestine

A wider and shorter organ, $1.5\,m$ in length, that absorbs water and salt from undigested food.

Pathogen

An organism causing disease to its host, such as viruses, bacteria, and eukaryotes.

Virulence

A term referring to the severity of the disease symptoms caused by a pathogen.

Energy

Defined as the capacity to do work.

Energy flow

The movement of energy through a series of organisms in an ecosystem.

Primary Producers

Organisms at the first trophic level, such as plants, that take energy from sunlight and convert it into organic material through photosynthesis.

Herbivores

Organisms at the second trophic level that use plants as food to perform metabolic functions like breathing, digestion, and growth.

Carnivores

Organisms at the third trophic level that feed on herbivores to derive energy for their growth and sustenance.

Food Chain

A linear network of links in a food web starting from producer organisms and ending at apex predator species, detritivores, or decomposer species.

Food Web

The system of natural interconnections between multiple food chains.

Food Chain Length

A metric quantified by the number of links between a trophic consumer and the base of the web.

Autotrophs

Primary producers that can use either solar energy or chemical energy to create complex organic compounds.

Chemotrophs

Forms of life that gain all their metabolic energy from chemosynthesis driven by hydrothermal vents rather than solar energy.

Decomposers

Organisms, such as bacteria and fungi, that feed on dead animals and break down organic compounds into simple nutrients returned to the soil.

Keystone Species

A species that has a large impact on the surrounding environment and keeps herbivores from depleting all foliage, preventing mass extinction.

Al-Jahiz

The Arab scientist and philosopher who first introduced food chains in the $10^{th}$ century.

Charles Elton

The author who popularized the food chain and introduced the food web concept in a book published in $1927$.

Limiting Factor

Any variable in an environment capable of limiting a process such as growth, abundance, or distribution of a population.

Liebig’s Law of the Minimum

A law stating that the growth of a population is regulated by the scarcest resource, not by those in abundance.

Blackman’s Law of Limiting Factor

A law stating that a biological or ecological process depending on multiple factors will have its rate limited by the slowest factor.

Shelford’s Law of Tolerance

A principle suggesting that the survival success of an organism depends on a complex set of environmental factors.

Density-Dependent Factors

Factors whose effect on a population is determined by the total size of the population, such as predation, disease, and resource availability.

Density-Independent Limiting Factor

A factor capable of limiting population growth, abundance, or distribution irrespective of population density.

Co-limiting Factor

A factor that causes an indirect restrictive effect or increases the effect of a direct limiting factor.

Resources

Substances within an environment required by an organism for growth, maintenance, and reproduction.

Carrying Capacity

The number of organisms within a population that an environment can sustain indefinitely without environmental degradation.

Fundamental Niche

The total range of environmental conditions suitable for an organism to exist in the absence of limiting factors.

Realized Niche

The actual amount of resources or environmental conditions that an organism is able to utilize within an ecosystem.

Symbiosis

A close and long-term interaction between two different species.

Mutualism

A type of symbiosis where both Species A and Species B benefit from the interaction.

Commensalism

A type of symbiosis where Species A benefits while Species B is unaffected.

Parasitism

A symbiotic relationship where the parasite gains benefits from the host, which in turn harms the host without killing it.

Host

The larger organism in a symbiotic relationship on which a smaller organism depends.

Symbiont

The smaller organism in a symbiotic relationship that lives inside the host.

Endoparasites

Parasites living inside the host’s body, such as Plasmodium falciparum.

Ectoparasites

Parasites living outside the host’s body, such as bedbugs.

Mesoparasites

Parasites that enter the opening of a host body and embed themselves only partially.

Fasciola hepatica

Also known as Liver fluke; a parasite that attaches to the liver and moves to tissue and bile.

Taenia solium

A parasite more than $3000^{mm}$ long that lives in the human gastrointestinal tract and spreads through under-cooked pork.

Photosynthesis

A process by which phototrophs convert light energy into chemical energy, which is later used to fuel cellular activities and stored in the form of sugars.

Phototrophs

Organisms that utilize photosynthesis to synthesize nutrients by using carbon dioxide, water, and sunlight.

Chloroplasts

The specific organelles where the process of photosynthesis exclusively takes place.

Photosynthetic pigments

Molecules such as chlorophyll a, chlorophyll b, carotene, and xanthophyll that enable the absorption of light energy.

Oxygen ($O_2$)

The waste product or by-product of photosynthesis that is liberated out into the atmosphere through the leaves.

Stomata

The openings through which carbon dioxide enters the plant during the process of photosynthesis.

Xylem vessels

The structures that carry water absorbed by the root hairs from the soil to the leaves.

Glucose ($C_6H_{12}O_6$)

A source of food for plants that provides energy for growth and development, produced using hydrogen from water and carbon dioxide.

Pigments

Molecules that impart color and absorb light at specific wavelengths while reflecting unabsorbed light.

Chlorophyll-a

The main pigment primarily used to capture light energy during photosynthesis.

Thylakoids

The parts of the chloroplasts where chlorophyll a, chlorophyll b, and carotenoids are present.

Light-dependent reaction

The first stage of photosynthesis, also referred to as the light reaction.

Light independent reaction

The second stage of photosynthesis, also known as the dark reaction.

Fermentation

A metabolic process that extracts energy from carbohydrates in the absence of oxygen through the action of enzymes.

Zymology

The science of fermentation.