Biology Chapter 5: Population Genetics and Homeostasis

When two species from a common ancestor develop different traits.

When two unrelated species develop similar traits due to similar environments.

Traits with a common evolutionary origin, even if they have different functions.

Traits with similar functions but different evolutionary origins.

Process where organisms with traits better suited to their environment survive and reproduce more.

A trait that helps an organism survive and reproduce in its environment.

Each individual has two alleles for a gene, which separate during gamete formation.

Alleles of different genes sort independently of each other during gamete formation.

A mode of reproduction where offspring arise from a single parent without the involvement of gametes.

Asexual reproduction offers benefits such as rapid population growth, maintenance of successful traits, and reduced energy investment.

The ability of an organism to maintain a stable internal environment despite external changes.

A mechanism where the body's response to a change opposes the initial change.

The process of maintaining a stable internal body temperature.

The target temperature for a specific organism.

The relationship between an organism's surface area and its volume.

The transfer of heat between an organism and its surroundings.

Microevolution refers to small-scale changes in allele frequencies within a population over time, while macroevolution encompasses larger-scale evolutionary changes, including the formation of new species, over long periods.

A theoretical model that describes a population that is not evolving. Five conditions must be met: no mutations, random mating, no natural selection, large population size, and no gene flow.

Any violation of the five conditions can disrupt equilibrium and lead to evolution. Mutations introduce new alleles, non-random mating favors certain traits, natural selection eliminates less fit individuals, small populations are more prone to random genetic drift, and gene flow introduces or removes alleles.

Sexual reproduction generates genetic diversity through recombination and independent assortment during gamete formation. This results in offspring with unique combinations of alleles from both parents.

Asexual reproduction produces genetically identical offspring (clones) because there is no mixing of genetic material. This leads to lower genetic diversity compared to sexually reproducing populations.

A species is a group of organisms that can interbreed and produce fertile offspring under natural conditions. Speciation is the process by which new species arise, often due to reproductive isolation and genetic divergence.

Reproductive isolation, which can be geographic, behavioral, temporal, or mechanical, is the initial step in speciation. Over time, isolated populations accumulate genetic differences leading to distinct species.

Allopatric speciation occurs when populations are geographically isolated, leading to divergence. Sympatric speciation occurs when populations diverge within the same geographic area, often due to behavioral or ecological differences.

Blubber, a thick layer of fat, provides insulation against cold water temperatures.

Feathers trap heat and create an insulating layer.

A body cavity between the mesoderm and endoderm in triploblastic animals, providing space for organs and aiding in mobility.

It enables directional movement, allowing for better coordination and efficient locomotion.

Radial symmetry, where body parts are arranged around a central axis.

Animals can either have radial symmetry or bilateral symmetry.

The concentration of sensory organs and a brain at the anterior (head) end of an animal.

Animals that develop three germ layers: ectoderm, mesoderm, and endoderm.

The amniotic egg, a defining feature of amniotes, possesses protective membranes that prevent water loss and allow reproduction in dry environments.

In placental mammals, the amniotic sac, chorion, yolk sac, and allantois, collectively known as extraembryonic membranes, provide protection, nourishment, and waste removal for the developing embryo.

Mammals are named for the presence of mammary glands, which produce milk to nourish their young.

Mammals, besides mammary glands, are distinguished by three other traits: hair or fur for insulation, three middle ear bones for enhanced hearing, and endothermy, the ability to regulate body temperature internally.

Primates possess grasping hands and feet with opposable thumbs, forward-facing eyes for depth perception, and relatively large brains.

Primate traits like grasping hands, forward-facing eyes, and large brains are adaptations for arboreal living, providing benefits like grasping branches, navigating trees efficiently, and improved visual coordination.

Homo sapiens first appeared in Africa about 300,000 years ago.

Homo sapiens last shared a common ancestor with chimpanzees around 6 to 7 million years ago.

Plants evolved adaptations to overcome challenges of living on land such as desiccation, structural support, and reproduction. This includes a waxy cuticle for water retention, vascular tissues for transport, and pollen for airborne reproduction.

Animals also faced challenges moving onto land such as desiccation, gravity, and oxygen availability. They evolved adaptations such as waterproof skin or exoskeletons, lungs for breathing air, and limbs for locomotion.

The amniote egg evolved in reptiles to protect the developing embryo in a dry, terrestrial environment and prevent desiccation.

Similar to the amniote egg, the plant seed evolved in seed plants (angiosperms and gymnosperms) to protect and nourish the developing embryo in a dry environment.

Plant cells have specialized structures that allow them to function effectively in their environment. These include cell walls for structural support, chloroplasts for photosynthesis, and large vacuoles for storage and support.

Animal cells lack cell walls and instead have a plasma membrane. They have smaller vacuoles compared to plants.

Fungal cells have a cell wall made of chitin, a hard material also found in insect exoskeletons. Like plants, they also contain vacuoles for storage.

Plants, animals, and fungi all exhibit a hierarchical organization from cells to tissues, organs, and organ systems. This allows for specialized functions and efficient integration of processes.

The formation of new species due to geographic isolation, preventing gene flow between populations, leading to genetic divergence.

The formation of new species within the same geographic area, driven by factors like behavioral changes, ecological differences, or genetic mutations.

Reproductive barriers that prevent mating or fertilization, like differences in mating behavior or habitat isolation.

Reproductive barriers that act after fertilization, resulting in hybrid inviability or sterility.

The fitness of hybrids relative to their parents influences the outcome of speciation. If hybrids have lower fitness, speciation is more likely to occur as parental populations remain distinct. Conversely, if hybrids have higher fitness, gene flow between species may prevent speciation.

A diagram that represents the evolutionary relationships between different species or groups, showing their common ancestry and divergence.

The length of a branch can represent the amount of evolutionary change or time that has passed since two species shared a common ancestor.

Scientists use shared derived traits, molecular data (DNA sequences), and fossil records to construct phylogenetic trees. The principle of parsimony is often used to determine the most likely tree, favoring the simplest explanation with the least number of evolutionary changes.

Prokaryotic cells are smaller, lack membrane-bound organelles and a nucleus. Eukaryotic cells are larger, have a nucleus, and contain membrane-bound organelles.

Prokaryotes have a single, circular chromosome located in the nucleoid region.

Eukaryotes have multiple linear chromosomes located inside the nucleus.

Prokaryotes reproduce asexually through binary fission, where a cell divides into two identical copies.

Genetic recombination occurs separately from reproduction, involving processes like transformation, transduction, and conjugation.

The process where a eukaryotic cell engulfs another prokaryotic cell, leading to the formation of an organelle. Example: Chloroplasts and mitochondria.

Organelles like chloroplasts and mitochondria have their own DNA, replicate independently, and have a double membrane.

An organism that causes disease. Some prokaryotes, like certain bacteria, can be pathogenic.

Bacteria evolve resistance to antibiotics quickly due to their high mutation rates, ability to share genes (horizontal gene transfer), and rapid reproduction.

Proteobacteria (contributed to mitochondria) and Cyanobacteria (contributed to chloroplasts) are believed to have played a role in the origin of eukaryotic cells.

Protists are a diverse group of eukaryotic organisms that don't fit neatly into the plant, animal, or fungal kingdoms. They are not a monophyletic group, meaning they don't share a single common ancestor.

Prokaryotes are small, simple cells without internal compartments. Microbial eukaryotes are larger, with internal compartments like nuclei and mitochondria. Multicellular eukaryotes have specialized cells, tissues, and organs.

Algae are photosynthetic protists that live in water. They are not a single group, but include green algae, red algae, and brown algae. These groups evolved photosynthesis independently.

Meristematic tissues are actively dividing cells responsible for plant growth. Permanent tissues are specialized cells with specific functions.

Meristematic tissues are found at the tips of roots and shoots (apical meristems), as well as in other areas of the plant body (lateral meristems).

Algae produce oxygen through photosynthesis and are the base of aquatic food webs, providing energy for other organisms.

Organisms that obtain energy by consuming other organisms. They cannot produce their own food through photosynthesis.

Fungi are heterotrophs. They release enzymes externally to break down food sources, then absorb the nutrients.

Plants use photosynthesis to convert sunlight, water, and carbon dioxide into energy.

Reproductive cells that can develop into a new organism without fertilization. They are often haploid, meaning they have one set of chromosomes.

Mushrooms are the fruiting bodies of some fungi, specifically basidiomycetes. They produce spores for reproduction.

Yeast refers to unicellular fungi, often used in baking and brewing. Mold refers to multicellular fungi with a filamentous structure (mycelium).

Fungi break down dead organic matter by secreting enzymes (external digestion). They have a large surface area (hyphae network) for efficient nutrient absorption.

A community of living organisms interacting with their physical environment.

The concentration of sensory organs and nervous tissue in the head region of an animal, forming a distinct head with a brain.

It enables more efficient processing of sensory information and coordination of movement, particularly for directional travel.

The three most diverse animal phyla are Arthropoda, Mollusca, and Chordata.

Sponges belong to this phylum. They lack tissues and organs, have porous bodies, and filter feed by drawing water through pores.

This phylum includes anemones and jellies. They have radial symmetry, a simple digestive cavity, and specialized stinging cells called cnidocytes.

This phylum includes gastropods, cephalopods, and bivalves. They have soft bodies, often with shells, and a mantle.

Earthworms belong to this phylum. They have segmented bodies, a coelom, and a closed circulatory system.

This phylum includes crustaceans, arachnids, and insects. They have exoskeletons, segmented bodies, and jointed appendages.

A hard, protective outer covering made of chitin that provides support and protection. It is shed and replaced as the arthropod grows.

The body of an arthropod is divided into segments, each with specialized appendages that perform specific functions.

Chordates are characterized by the presence of a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

The primary difference between vertebrate and invertebrate chordates is the presence of a vertebral column (backbone) in vertebrates.

Evolution of tetrapods involved the modification of fins into limbs with stronger, weight-bearing bones to support their weight on land.

Reptiles have scaly skin, lay amniotic eggs, and are more resistant to water loss, allowing them to live in drier environments. Amphibians have moist skin, lay eggs in water, and are reliant on moist environments.

Amniotes, including reptiles, birds, and mammals, possess an amniotic egg, which protects the embryo in a dry environment and allows for terrestrial reproduction.

Extraembryonic membranes in placental mammals (amnion, chorion, yolk sac, allantois) provide protection, nourishment, and waste removal for the developing embryo.