BISC208 exam 2

What is an animal?

Animals are multicellular eukaryotes.

Animal cells

Animal cells lack cell walls.

Animal nutrition

Animals use ingestion, the eating of food.

Fungi nutrition

Fungi absorb nutrients after digesting food outside their body.

Animals classification

Animals are heterotrophs.

Animal reproduction

Nearly all animals reproduce sexually.

Adult animals ploidy

Adults are diploid.

Gametes description

Gametes are haploid, and fuse to form a diploid zygote.

Blastula formation

The zygote divides by mitosis to form a hollow ball of cells called a blastula.

Gastrula formation

One side of the blastula folds in and the cells rearrange to form a gastrula with three embryonic layers.

Endoderm

Endoderm forms a lining of the future digestive tract.

Ectoderm

Ectoderm forms an outer layer that will give rise to the skin and nervous system.

Mesoderm

Mesoderm forms a middle layer that will give rise to muscles and most internal organs.

Animal diversification began when

Animal diversification began more than half a billion years ago.

Oldest animal fossils age

The oldest generally accepted animal fossils that have been found are 575–550 million years old.

Cambrian explosion timing

Animals diversified rapidly around 530 million years ago, during the “Cambrian explosion.”

Cambrian explosion causes

May have been caused by increasingly complex predator-prey relationships and/or an increase in atmospheric oxygen.

Chordata description

Of the 35 or so animal phyla, only one phylum (Chordata) includes vertebrates, animals with a backbone.

Invertebrates definition

Roughly 96% of animals are invertebrates, animals that lack a backbone.

Porifera description

Sponges have lost their germ layers and lack true tissues.

Spongocoel

Water is drawn in through pores into a central cavity called spongocoel.

Osculum

Water flows out through a large opening at the top, called osculum.

Choanocytes

There are specialized cells called choanocytes that line the spongocoel which trap and eat small particulate matter.

Sponges reproduction description

Sponges are hermaphrodites, but can reproduce both sexually and asexually.

Sponges asexual reproduction

A small fragment or bud may detach and form a new sponge.

Cnidaria body forms description

Most cnidarians exist in two body forms: sessile polyp or motile medusa.

Polyp description

The polyp form has a tubular body with an opening at the top end surrounded by tentacles.

Medusa description

The free swimming medusa form has an umbrella shaped body.

Cnidocytes definition

Cnidarians consist of stinging cells called cnidocytes, which function in defense or capture of prey.

Nematocysts definition

Cnidocytes contain nematocysts, powerful capsules with an inverted coiled and barbed thread.

Cnidocil definition

Hair-like structures called cnidocil detect chemical stimulus and lead to discharge of the nematocyst.

Cnidarian feeding process

The filament penetrates the prey, injecting toxin causing immobilization and passing into the mouth by tentacles.

Lophotrochozoa definition

Lophotrochozoa is a clade that consists of the following phyla: Platyhelminthes, Rotifera, Bryozoa, Brachiopoda, Mollusca, Annelida.

Platyhelminthes description

Platyhelminthes or flatworms have three distinctive embryonic germ layers – triploblastic.

Platyhelminthes body cavity

They lack a coelom and are considered acoelomates.

Platyhelminthes digestive system

Contain only one opening that serves as mouth and anus.

Platyhelminthes symmetry

They are bilaterally symmetrical.

Platyhelminthes reproduction

Reproduction is either sexual or asexual.

Rotifera name origin

Members of phylum Rotifera get their name from their ciliated crown or corona.

Rotifera body type

They are pseudocoelomates.

Rotifera digestive system

They have a separate opening for mouth and anus.

Mastax definition

The mouth opens into a circular, muscular pharynx called a mastax.

Rotifera reproduction description

Unfertilized diploid eggs develop into females by parthenogenesis.

Mollusca description

Mollusks constitute a very large phylum with over 100,000 living species.

Mollusca body feature

One common feature is their soft body often under a protective external shell.

Mollusca body plan details

A muscular foot used for movement, a visceral mass containing internal organs, and a mantle which secretes a shell.

Mollusca body type

They are coelomates.

Mollusca circulation

Have an open circulatory system with a heart that pumps hemolymph.

Metanephridia definition

A specialized excretory organ that removes nitrogenous and other wastes.

Radula definition

A protrusible, tongue-like organ used for feeding.

Annelida description

Annelids are segmented worms including marine worms, tube worms, earthworms and leeches.

Segmentation advantage 1

Components repeated in each segment allow continued function if one segment fails.

Segmentation advantage 2

The fluid-filled coelom acts as a hydrostatic skeleton.

Segmentation advantage 3

Segmentation permits specialization of segments.

Setae definition

Chitinous bristles present on each segment.

Parapodia definition

Fleshy, footlike structures that help with movement.

Annelid nervous system description

Cerebral ganglia and a large ventral nerve cord.

Annelid circulatory system

Closed circulatory system.

Annelid respiration

Occurs directly through the skin surface.

Annelid digestive system

Complete with mouth, pharynx, esophagus, crop, gizzard, intestine and anus.

Nematoda description

Nematodes are small, thin worms ranging from less than 1mm to 5cm.

Nematoda habitat

Found in all types of habitats and some are parasitic.

Nematoda cuticle

A tough cuticle made primarily of collagen.

Nematoda body type

Pseudocoelomates.

Nematoda digestive system

Complete digestive system with mouth, pharynx, intestine and anus.

Nematoda reproduction

Usually sexual with internal fertilization.

Arthropoda description

The most diverse phylum on Earth including spiders, insects and crustaceans.

Arthropoda proportion

About three-quarters of all described living species are arthropods.

Arthropoda success features

Exoskeleton, segmentation and jointed appendages.

Exoskeleton composition

Made of chitin and protein.

Exoskeleton function

Impermeable to water and helps conserve water.

Jointed appendages function

Permit complex movements and specialized functions.

Neuron dendrites

Dendrites receive signals and carry them to the cell body.

Cell body function

Contains nucleus and relays information to axon.

Axon function

Transmits signals from the cell body.

Axon terminal function

Final relay of information.

Action potential definition

An all-or-none response.

Threshold description

Membrane potential either exceeds threshold or does not.

Propagation description

Once begun, an action potential is self-propagating.

Signal intensity encoding

Encoded in frequency of action potentials.

Signal production cause

Differences in ion concentration and membrane permeability.

Homeostasis definition

Maintaining a relatively stable internal environment.