animals

Question 1

What are the 4 characteristics of animals?

Answer 1

Cell structure and Specialization, Nutritional mode, reproduction, development.

Question 2

How are cells and tissues interconnected in animals?

Answer 2

extracellular, structural proteins

Question 3

What two tissues are characterisitic of animals?

Answer 3

muscle and nervous

Question 4

What is the nutritional mode of animals?

Answer 4

phagotrophic chemoheterotrophs

Question 5

How does sexual reproduction in animals work?

Answer 5

Gametes are rpoduced by meiosis, fuse to form diploid zygot

Question 6

3 forms of asexual reproduction in animals?

Answer 6

Fragmentation, fission, budding

Question 7

What is parthenogenesis?

Answer 7

Development of an unfertilized egg cell into an embryo

Question 8

What are 2 benefits of asexual reproduction?

Answer 8

Rapid population growth in favourable conditions.
Advantageous when opportunities for sexual reproduction are limited.

Question 9

How does a zygote develop into an embryo? (3 steps)

Answer 9

1) Rapid mitotic divisions called cleavage form an 8-cell embryo
2) More cleavage forms a blastula with a blastocoele
3) Gastrulation forms a gastrula with a ectoderm and endoderm

Question 10

What is the archenteron?

Answer 10

Pouch formed in the gastrula which opens to the outside via the blastospore.

Question 11

What are Hox genes and what do they do?

Answer 11

Highly conserved genes that regulate embryonic development by regulating development along the anterior-posterior axis

Question 12

Direct development vs Indirect development

Answer 12

Direct development is when the animal after birth is a juvenile version of its adult form.
Indirect development is when an animal has a larval stage that is morphologically and behaviourally different from the adult stage.

Question 13

Are all animals motile?

Answer 13

Yes, at atleast one stage in their life

Question 14

What are the two kinds of symmetry in animal body plans?

Answer 14

Radial symmetry - usually sessile
Bilateral symmetry - specialized for directional movement
- also have cephalization

Question 15

What are the 3 embryonic tissue layers and what do they give rise to?

Answer 15

Ectoderm - skin + nervous system
Endoderm - lines developing digestive tube
Mesoderm - muscle tissue

Question 16

What is the coelom and what does the coelom do?

Answer 16

fluid-filled body cavity where internal organs develop within the mesoderm
- allows organs to shift without deforming body
- cushions internal organs
- hydrostatic skeleton

Question 17

What is the hemocoel and what does it do?

Answer 17

Forms between the mesoderm and endoderm and arises from the blastoceoel.
- contains hemolymph which is analagous to blood and circulated throughout the body cavity in an open ciruculatory system by the heart
- involved in circulation, nutrient transport, waste removal and may function as a hydrostatic skeleton

Question 18

What are animals with coeleoms called?

Answer 18

coelomates.

Question 19

What are the 2 forms of development in bilateral triploblastic animals? (+ features)

Answer 19

Protostome development
- spiral, determinate cleavage
- mouth forms from blastopore
- coelom forms by splitting of solid masses of mesoderm
Deuterostome development
- radial, indeterminate cleavage
- anus forms from blastospore
- coelom forms by outpocketing of mesoderm from archenteron

Question 20

What are the basal animals?

Answer 20

sponges

Question 21

What is the clade of animals with true tissues?

Answer 21

Eumetazoa

Question 22

What are the 3 major clades of bilaterians?

Answer 22

Deuterostomia, Ecdysozoans, Lophotrochozoans

Question 23

How are choanoflagellates related to animals? (2 items)

Answer 23

1) cell morphology - choanoflagellate cells + collar cells of sponges are the same
- similar cells found in other animals
2) DNA sequence homology
- molecular phylogeny confirms relationship

Question 24

What are some hypotheses for the Cambrian explosion?

Answer 24

• Evolution of predators and prey led to developpment of more complex body structures
• Neoproterozoic Oxygenation event led to more energetic lifestyles and greater body size
• Evolution of Hox genes facilitated diversification of body forms