Biology 2 Exam 2

4 General Characteristics of Animals

Multicellularity

Heterotrophic metabolism

Internal digestion

Movement and nervous systems

Cleavage

Early cell divisions of an embryo.

Patterns of cleavage characterize major animal

groups.

Radical Cleavage

Yolk is evenly distributed throughout the egg cytoplasm; zygote and descendant cells divide completely and evenly.

Spiral Cleavage

Complex permutation of radial cleavage (new cells at angles to existing ones)

Diploblastic

two cell layers

Ectoderm and Endoderm

Triploblastic

three cell layers

Ectoderm, Endoderm and Mesoderm

When do cell layers form?

during gastrulation in the embryo

Gastrulation

embryo is a hollow ball of cells that indents to form a cavity, the blastopore

Blastopore

a cavity formed during gastrulation

Bilaterians

bilateral symmetry during embryonic development

All triploblastic animals are….

bilaterians

Protostomes

blastopore develops into the mouth; anus forms later (e.g. insects, snails)

Deuterostomes

blastopore develops into the anus; mouth develops later (e.g. vertebrates, starfish)

Body Plan

general structure, arrangement of organ systems, and integrated functioning of body parts.

Five Key Features of a Body Plan

symmetry

body cavity structure

segmentation

external appendages

nervous system

Symmetry

overall shape

Symmetrical

can be divided along at least one plane into similar halves

Radial Symmetry

body parts arranged around a central axis

Bilateral Symmetry

can be divided into mirror image halves on only one plane

Asymmetrical

no plane of symmetry (placozoans and sponges)

Cephalization

concentration of sensory organs and nerve tissues at the anterior end, or head

correlated with bilateral symmetry

evolutionarily favored, anterior end encounters the environment first

Acoelomate

no fluid-filled body cavity Space between gut and body wall is filled with cells called mesenchyme; move by beating cilia.

Pseudocoelomate

body cavity is a pseudocoel, a fluid-filled space in which internal organs are suspended; no mesoderm surrounding internal organs.

Coelomate

body cavity is a coelom that develops within the mesoderm; lined with a layer of muscular tissue, called peritoneum. Coelom is enclosed on both the inside and the outside by mesoderm.

Hydrostatic Skeletons

when muscles contract, fluid is pushed to another part of the cavity, which causes that region to expand.

body cavities can function as these

Segmentation

facilitates specialization of body regions; also allows animal to alter body shape and control movements precisely.

What was radiation of the arthropods based on?

changes in a segmented body plan

Appendages

enhance an animal’s ability to move around; also include antennae, claws, mouthparts, and reproductive organs

Nerve Nets

diffuse nervous systems in animals such as ctenophores and cnidarians

What group of animals have well-coordinated central nervous systems?

bilaterians

Which four animal groups are not bilaterians?

sponges, ctenophores, placozoans, cnidarians

Characteristics of Sponges

have no distinct embryonic cell layers and no true organs

spicules

What are glass sponge and demosponge spicules made of?

silicon dioxide

What are calcareous sponge spicules made of?

calcium carbonate

Spicules

hard skeletal elements found in sponges

Characteristics of Ctenophores?

(comb jellies)

radial symmetry, diploblastic

move by beating cilia arranged on eight comblike plates called ctenes

Ctenes

comblike plates found in ctenophores, aid in movement

Characteristics of Placozoans

very simples, only 4 cell types; diploblastic

Two life stages: pelagic swimming stage and stage that adheres to surfaces

Characteristics of Cnidarians

Gastrovascular cavity

Life cycle with sessile polyp and motile medusa stages.

Nematocysts

Gastrovascular Cavity

functions in digestion, circulation, gas exchange, and as a hydrostatic skeleton

Nematocysts

are specialized harpoon-like structures with toxins, used to capture large prey.

Polyp Life Cycle Stage

a sessile (attached) and typically asexual phase

(cnidarians)

Motile Medusa Life Cycle Stage

free-swimming, bell- or umbrella-shaped adult phase

(cnidarians)

Heterotroph

require preformed organic molecules as sources of energy and chemical building blocks

What does the second law of thermodynamics tell us?

any organized system, left to itself, tends to lose organization and become more random

What does it take for animals to create and maintain organization?

energy

Name Three Types of Feeding

predation, suspension feeding, symbiosis

Nutrition

study of how animals meet their energy needs for both chemical substances and energy

Essential Nutrients

required but cannot be synthesized by the animal

Standard Amino Acids

the 20 amino acids animals need to build proteins; animals can synthesize some of these (nonessential)

Essential Amino Acids

the ones that cannot be synthesized and must come from food

Essential Fatty Acids

includes omega-3 and omega-6 fatty acids

(3 and 6 refer to the # carbon position of the last double bond)

What are the eight essential amino acids for adult humans?

PVT TIM HALL

Grains:

Tryptophan

Methionine

Grains and Legumes:

Valine

Threonine

Phenylalanine

Leucine

Legumes:

Isoleucine

Lysine

Essential Vitamins

vitamin A (vision)

vitamin K (blood clotting)

Essential Minerals

chemical elements that animals require in addition to C, O, H and N

Calorie

amount of heat needed to raise 1 gram of H2O 1oC

food calories are actually in kilocalories

Metabolic Rate

amount of chemical bond energy consumed and converted to heat per day

Name the Three Types of Food Molecules

lipids, carbohydrates, proteins

How can metabolic rate be measured?

by determining rate of O2 consumption

What happens when organic matter is oxidized during aerobic metabolism?

O2 is used, while heat is produced

Basal Metabolic Rate (BMR)

measured when animals is a comfortable thermal environment and has not eaten recently

Scaling Relationships

animal characteristics as functions of body size

BMR per gram body weight decreases as animal size increases.

Small mammals need more food per gram of body weight than large mammals do

Interstitial Fluids

fluids that bath cells in an animal’s body (the internal environment)

Regulation

occurs when the internal environment stays constant even as the external environment changes

provides stability but is energetically expensive, tends to increase metabolic rates

Regulators

Animals that can maintain constant internal conditions such as temperature

Conformers

the internal environment varies so that it always matches the external environment.

Conforming

energetically cheap but the animal’s cells must be able to cope with changes in their environment

Extracellular Fluid

includes blood plasma and interstitial fluid

Intracellular Fluid

fluid inside cells

What are fluid compartments separated by?

epithelia and cell membranes

Epithelium

sheet of epithelial cells that covers a body surface or organ or lines a body cavity

Single Epithelium

single layer of cells on a nonliving basement membrane; lines all blood vessels, intestines, and other tubules

Epithelium Functions

Pumps ions between fluids on either side of the epithelium

Secretes substances such as hormones, mucus, digestive enzymes, milk, gut

Absorbs nutrients from the gut

Serves sensory functions, including smell and taste

What roles cell membranes play?

pumps ions between the intra and extra cellular fluid

play key roles in producing and receiving physiological signals

control diffusion of ions/molecules

Tissue

assemblage of cells of similar type

Organ

two or more types of tissue with a defined structural relationship to each other

Multi-Organ System

multiple organs working together

Homeostasis

refers to stability of the internal environment and the mechanisms that maintain it

It is a parallel concept to regulation and has the same pros and cons; it is energetically expensive

Humans, and many other animals exhibit high degrees of homeostasis, but some exhibit little

Homeotherms

animals that maintain a constant internal body temperature (thermoregulation); e.g., mammals and birds

Thermoneutral Zone (TNZ)

is a range of external temperatures in which metabolic rate is

minimal and does not change with external temperature