Animalia Introduction

Question 1

What are 3 characteristics of cell structure in animals?

Answer 1

1. they are multicellular eukaryotes
2. they lack cell walls
3. their bodies are held together by structural proteins called collagen

Question 2

What are tissues?

Answer 2

tissues are groups of cells that have a common structure, function or both

Question 3

What type of feeders are animals?

Answer 3

chemoheterotrophs: they can’t make their own carbon-based food and must consume other organisms for nutrients

Question 4

How to animals typically reproduce?

Answer 4

animals reproduce via sexual reproduction. When a motile (moving) sperm fertilizes a non-motile haploid egg which forms diploid zygote

Question 5

What is a homeobox?

Answer 5

homeobox is a region on DNA (180 base pairs) that are highly conserved

• they are regulatory genes that produce proteins and can turn other genes on or off [they do not produce traits, they tell other genes to turn on or off in trait production
• homeoboxes control the anterior to posterior developmental sequences of embryos (tells embryo which part it will develop)

Question 6

What are Hox genes?

Answer 6

a group of related genes that control the body plan of an embryo along the anterior-posterior axis (head to tail axis)

• aka genes that code for the thorax, genes that code for the trunk…etc..
• if these genes are altered in anyway, it may cause weird occurrences like a third arm, or an arm instead of a leg.
• Hox genes turn different segments in the animals on/off

Question 7

Describe the reproductive process and embryonic development of most animals

Answer 7

1. the haploid motile sperm fertilizes the haploid non-motile eggs to form a diploid zygote
2. the diploid zygote goes through mitotic cell divisions through a process called cleavage
3. the cleavage breaks off into a 8 cell stage and then breaks off again into a blastula (a multicellular, hollow cell)
4. the blastula undergoes gastrulation, which forms a gastrula (with different layers of embryonic tissues)
   The gastrula’s different germ layers give rise to the tissues and organs of the animal embryo. It forms a blastopore and ectoderm and endoderm

Question 8

What are 2 modes of animal development?

Answer 8

1. direct development –> embryo continues gradually on towards adult form … like humans
2. indirect development –> theres an intervening stage like larvae, whose morphology, behaviour and habitat differs greatly from sexually mature adult stage… this is like caterpillars and butterflies