Animals

Question 1

Characteristics of animals

Answer 1

• Are Heterotrophic
• Use oxygen for respiration
• Do not have a cell wall
• Have specialized cells:
  occurs during embryonic development, where cells begin to differentiate from one another to perform specific functions
• Have nerve cells (with the exception of the Porifera phylum)

Question 2

What is developing embryo, and three layers

Answer 2

Three layers of cells form during embryonic development, called germ layers:
- Endoderm
- Ectoderm
- Mesoderm

Question 3

Ectoderm

Answer 3

Outer layer, develops into skin and nervous system

Question 4

Endoderm

Answer 4

Inner layer, develops into the inner lining of internal systems

Question 5

Mesoderm

Answer 5

Middle layer, develops into the circulatory, reproductive, excretory, and muscular systems

Question 6

Two key divisions of animals

Answer 6

• Radial symmetry
• Bilateral symmetry

Question 7

Radial symmetry

Answer 7

• Symmetry around a central axis
• Only found in phylum Cnidaria
• Ex. Jellyfish

Question 8

Bilateral symmetry

Answer 8

• Symmetry around a midline
• Ex. Humans

Question 9

Branches of bilateral symmetry

Answer 9

• Protostomes
• Deuterostomes

Question 10

Protostomes

Answer 10

• Mouth forms before the anus in embryonic development
• Are Invertebrates

Question 11

Deuterostomes

Answer 11

• Anus forms before the mouth in embryonic development
• Can be vertebrates or invertebrates

Question 12

Protostome invertibrates

Answer 12

• Arthropoda
• Nematoda (roundworms)
• Annelida (segmented worms)
• Mollusca
• Rotifers
• Platyhelminthes (flat worms)

Question 13

Arthropoda

Answer 13

• Examples are Insects and spiders
• Segmented with jointed appendages
• Antennae – sensory system
• Exoskeleton made of chitin

Question 14

Nematoda (round worms)

Answer 14

• Examples are Dog Heartworms
• Unsegmented, cylindrical bodies, with complete digestive tracts

Question 15

Annelida (segmented worms)

Answer 15

• Examples are earthworms
• True digestive track (goes in one end comes out the other)

Question 16

Mollusca

Answer 16

• Examples are helix and octopus
• Many have hard shell made of calcium carbonate

Question 17

Rotifers

Answer 17

• Example is a Rotifer
• Aquatic, use cilia to direct food to mouth

Question 18

Platyhelminthes (flatworms)

Answer 18

• Examples are tapeworms
• Flattened, unsegmented
• Single opening for digestive cavity.

Question 19

Deuterostomes Segments

Answer 19

• Vertebrates
• Invertebrates

Question 20

Deuterostome invertebrates

Answer 20

• Echinoderms
• Example is a starfish

Question 21

Deuterstome vertebrates

Answer 21

• Phylum = chordata!
• Have the presence of a backbone, which protects their dorsal nerve cord (spinal cord in humans)
• Most also have a cranium (skull) that protects the brain, which also connects to the nerve cord
• Have advanced organ systems and exhibit complex behaviors
  There are 5 vertebrate classes:
• Fish
• Amphibians
• Reptiles
• Birds
• Mammals

Question 22

Special cases

Answer 22

Porifera
- Example is a sponge
- No symmetry
- No specialized tissue
Cnidaria
- Example is a jellyfish
- 2 germ layers
- 1 hole (mouth and anus)
- No organs

Question 23

How eukaryotic cells developed into multicellular organisms

Answer 23

• Spherical arrangement of cells in a colony might have become indented, forming a hollow cavity which became a cavity that specializes in digestion
• The cells became specialized and formed feeding cells which used the hollow cavity to capture and digest food.
• The cells outside the hollow cavity specialized in other areas as they were not needed for digestion
• We can see similar arrangements and processes occurring in certain animals today.
• This idea of cells becoming specialized to fit their environment and needs is how lots of our cells were formed.