bio exam 2 full set as of 10/15

Evolution

"descent with modification" and change in genetic composition of a population from generation to generation.

Biological species concept

The ability to interbreed, not on physical similarity.

Limitations of biological species concept

Cannot evaluate the reproductive isolation of fossils or extinct taxa; does not apply to organisms that reproduce asexually; hybridization still occurs occasionally between morphologically and ecologically distinct organisms.

Morphological species concept

Can be applied to asexual and sexual organisms.

Ecological species concept

Can be applied to asexual and sexual organisms; emphasizes the role of disruptive information on gene flow as organisms adapt to different environments.

Reproductive isolation

The existence of biological factors (barriers) that obstruct members of a species from interbreeding and producing viable, fertile offspring.

Prezygotic barriers

Block fertilization from occurring.

Postzygotic barriers

May contribute to reproductive isolation after the hybrid zygote is formed.

Allopatric Speciation

Population forms a new species while geographically isolated from its parent population.

Sympatric Speciation

A subset of a population forms a new species without geographic separation.

Hybrid Zone

A region in which members of different species meet and mate, producing at least some offspring of mixed ancestry.

Outcomes of hybridization

Reinforcement (strengthening of reproductive barriers), Fusion (weakening of reproductive barriers), Stability (continued production of hybrid individuals).

Animal characteristics

Multicellular, heterotrophic (cannot make food), tissues that develop from embryonic layers, sexual reproduction, diploid dominant.

Gastrulation

Formation of belly in fertilization.

Bilaterally symmetrical animals

Have only 1 plane that can cut symmetrically; have dorsal and ventral sides, as well as head and tail ends.

Radially symmetrical animals

Can be cut symmetrically in more than one plane.

Diploblastic

Embryos may be diploblastic (two germ layers) or triploblastic (three germ layers).

Coelom

A body cavity that may be present in triploblastic animals.

Protostome

Organisms that develop 'mouth first'.

Deuterostome

Organisms that develop 'mouth second'.

Animal Phylogeny Overview

All animals share a common ancestor; sponges are the sister group to all other animals.

Basal eumetazoans

Are diploblastic and generally have radial symmetry.

Bilateria

Most animal phyla belong to this clade.

Phyla examples

Echinodermata (starfish), Arthropoda (butterflies), Chordata (humans), Cnidaria (jellyfish), Mollusca (snails), Nematoda (roundworms), Platyhelminthes (flatworms), Porifera (sponges).

Deuterostomes

"mouth formed second"

Chordates

Dorsal hollow nerve cord

Notochord

A flexible rod that provides support

Endostyla

Thyroid gland in chordates

Post-anal tail

A tail that extends beyond the anus

Pharyngeal slits

Changes into mouth and throat structures

Mammalia

Characterized by hair and milk production

Bipedalism

Walking on two legs

Human brain

Large brain capable of language, symbolic thought, and artistic expression

Reduced jawbones

Smaller jaw structure compared to other apes

Shorter digestive tract

Adaptation in humans for diet

Extreme endurance runner

Unique ability of humans to run long distances

Throwing accuracy

Ability to throw objects with precision

Homo erectus

Species with a bigger brain than earlier hominins

Australopiths

Early hominins known for better tools and bipedal adaptations

Homo habilis

Known as 'handy man', with smaller brain and long-distance walking

Homo neanderthalensis

Species with a bigger brain than modern humans, known for complex tools

Homo sapiens

Known as 'thinking man', interbred with Neanderthals and Denisovans

Hominins

Group of species that includes modern humans and their ancestors

Rate of exchange

Proportional to surface area and volume

Interstitial fluid

Clear, watery substance filling spaces between cells

Circulatory fluid

Blood and lymph that transport oxygen, nutrients, hormones, and waste

Animal Nutrition

Diet must supply chemical energy, organic building blocks, and essential nutrients

Bulk feeding

Eating large pieces of food, e.g., a cat eating a rat

Fluid feeding

Sucking nutrient-rich fluids, e.g., a mosquito with needle-like mouthpart

Chemical breakdown

Enzymatic breakdown of macromolecules into subunits

Intracellular digestion

Digestion occurring within food vacuoles inside cells

Extracellular digestion

Digestion occurring in a tube that runs through the body

Gastrovascular cavity

Single opening that digests and distributes nutrients

Alimentary canal

"Complete" digestive tract running from mouth to anus

Mammalian digestive system

Includes mechanical breakdown in the oral cavity and chemical breakdown in the stomach and intestines

Large intestine

Colon, cecum, + rectum

Mutualism

Interaction between two species that benefits both of them

Microbiome

Collection of microorganisms living in and on the body

Circulatory system

Moves materials between organs

Respiration

The movement of air or dissolved gases into and out of the lungs

Diffusion

Movement of something from an area of high concentration to low concentration

Ventilation

Breathing

Cardiovascular System

A network of organs and vessels that transport blood throughout the body

Arteries

Carry blood away from the heart

Capillaries

Allow the transfer of substances through their walls

Open Circulatory Systems

Blood is not confined to vessels

Closed Circulatory System

Blood is confined to vessels

Hemolymph

Interstitial fluid in open circulatory systems

Veins

Carry blood towards the heart

Tracheal System

Network of air tubes branching throughout the body in arthropods

Cutaneous Respiration

Respiration through the skin covering the body

Gills

How fish breathe underwater

Countercurrent Exchange

Exchange of a substance or heat between two fluids flowing in opposite directions

Positive Pressure Breathing

Inflating lungs by forced air flow

Negative Pressure Breathing

Air is pulled into the lungs

A vian Respiratory System

Air moves over gas exchange surfaces in only one direction

Homeostasis

Maintenance of a 'steady state' in the internal environment despite fluctuations in the external environment

Temperature Regulators

Organisms that change in the face of external temperature fluctuations

Temperature Conformer

Allow internal conditions to change in accordance with external temperature

Negative Feedback

A change in a variable triggers a response that counteracts the initial change

Endothermic

Warmed mostly by heat generated by metabolism

Exothermic

Gain most of their heat from external sources

Bioenergetics

The overall flow and transformation of energy in an animal

Metabolic Rate

The sum of all energy an animal uses in a unit of time

Basal Metabolic Rate (BMR)

Metabolic rate of endotherms at rest

Standard Metabolic Rate (SMR)

Metabolic rate of ectotherms at rest

Torpor

Physiological state of decreased activity and metabolism

Hibernation

Long-term torpor that is an adaptation to winter cold and food scarcity

Estivation

Long-term torpor that is an adaptation to summer heat and limited water

Osmoregulation

Processes by which animals control solute concentrations and balance water gain and loss

Osmoconformer

Are isosmotic with their surroundings and do not regulate their osmolarity

Osmoregulator

Expend energy to control water uptake and loss in a hyperosmotic or hypoosmotic environment

Excretion

Ways of ridding the body of ammonia and other metabolic waste products

Ammonia

Very toxic, soluble in water, and diffuses across cell membranes

Urea

Low toxicity and high solubility in water; conversion of ammonia to urea is energetically expensive

Uric Acid

Somewhat non-toxic with little water solubility

Hybrid

An offspring resulting from the mating of two different species.

Heterotroph

An organism that cannot produce its own food and must consume other organisms.

Hox Genes

A group of related genes that control the body plan of an embryo along the head-tail axis.

Zygote

The fertilized egg that results from the union of sperm and egg.