Biology 121 Final Exam UPDATED Exam
Questions and CORRECT Answers
How did animals evolve? - CORRECT ANSWER - Animals are heterotrophs that evolved
from colonial protists.
•the first animal evolved around 600 million years ago in ancient seas
Cambrian Explosion (540 mya) - CORRECT ANSWER - -Established most animal phyla by
500 mya
Heterotrophs vs Autotrophs - CORRECT ANSWER - •Animals are heterotrophs. They obtain
food from their environment.
-Heterotrophs are also called consumers.
•In contrast, autotrophs are organisms that make their own food (like plants).
-Autotrophs are also called producers.
Animals share common features - CORRECT ANSWER - Most digest food inside their body.
Are motile during at least part of their life cycle. Have unwalled cells. Muscles, reproductive
system, nervous system, etc.
Developmental stages
Animal Body plans - CORRECT ANSWER - •Early animals had no body symmetry (ex.
Sponges)
•Radial symmetry
-Having parts arranged around a central axis, like spokes around a wheel
•Bilateral symmetry
,-Having paired structures so the right and left halves are mirror images
-Cephalization = Having a concentration of nerve and sensory cells at the head end (move head
first; seek food and detect threats)
Invertebrates - CORRECT ANSWER - Most animals have no backbone
9 Major Animal Phyla - CORRECT ANSWER - sponges, cnidarians, flatworms, annelids,
mollusks, roundworms, arthropods, echinoderms, chordates
Sponges and Cnidarians - CORRECT ANSWER - Mostly marine
•Sponges lack body symmetry and tissues.
•Cnidarians are radially symmetrical; they have tissues and stinging cells.
Sponges - CORRECT ANSWER - Longest evolutionary history of all animals
1.Aquatic invertebrates
2.NO Symmetry
3.NO Tissues, NO organs
4.Filter food from the water
5.All digestion is intracellular
6.Have a porous body
7.Are hermaphrodites
(produce both eggs and sperm)
8.The ciliated larva is the only motile stage
Sponge lack of tissue - CORRECT ANSWER - •Sponges lack tissues
-However, they do have specialized cells that perform specific functions.
, Every cell must be in contact with the environment
Cnidarians - CORRECT ANSWER - 1.Invertebrates with radial symmetry
2.Cells organized into tissues
3.Are marine predators
4.Mouth surrounded by tentacles
5.Uses stinging cells to capture food
6.Two distinct body forms
•Polyp (sea anemone)
•Medusa (jelly)
Include: sea anemones, hydras, corals, and jellies
Cnidarian Stinging- Nematocyst - CORRECT ANSWER - Nematocyst = stinging organelle
unique to cnidarians
help capture prey and deter predators
When trigger is touched, water diffuses into the capsule
Pressure builds up, the thread turns inside out, and the barbed tip pierces prey
Flatworms, Annelids, and Roundworms - CORRECT ANSWER - -Share similar body shape
-Different evolutionary heritage
Flatworms - CORRECT ANSWER - Lack digestive tract
1.Bilateral symmetry
2.Gastrovascular cavity
Questions and CORRECT Answers
How did animals evolve? - CORRECT ANSWER - Animals are heterotrophs that evolved
from colonial protists.
•the first animal evolved around 600 million years ago in ancient seas
Cambrian Explosion (540 mya) - CORRECT ANSWER - -Established most animal phyla by
500 mya
Heterotrophs vs Autotrophs - CORRECT ANSWER - •Animals are heterotrophs. They obtain
food from their environment.
-Heterotrophs are also called consumers.
•In contrast, autotrophs are organisms that make their own food (like plants).
-Autotrophs are also called producers.
Animals share common features - CORRECT ANSWER - Most digest food inside their body.
Are motile during at least part of their life cycle. Have unwalled cells. Muscles, reproductive
system, nervous system, etc.
Developmental stages
Animal Body plans - CORRECT ANSWER - •Early animals had no body symmetry (ex.
Sponges)
•Radial symmetry
-Having parts arranged around a central axis, like spokes around a wheel
•Bilateral symmetry
,-Having paired structures so the right and left halves are mirror images
-Cephalization = Having a concentration of nerve and sensory cells at the head end (move head
first; seek food and detect threats)
Invertebrates - CORRECT ANSWER - Most animals have no backbone
9 Major Animal Phyla - CORRECT ANSWER - sponges, cnidarians, flatworms, annelids,
mollusks, roundworms, arthropods, echinoderms, chordates
Sponges and Cnidarians - CORRECT ANSWER - Mostly marine
•Sponges lack body symmetry and tissues.
•Cnidarians are radially symmetrical; they have tissues and stinging cells.
Sponges - CORRECT ANSWER - Longest evolutionary history of all animals
1.Aquatic invertebrates
2.NO Symmetry
3.NO Tissues, NO organs
4.Filter food from the water
5.All digestion is intracellular
6.Have a porous body
7.Are hermaphrodites
(produce both eggs and sperm)
8.The ciliated larva is the only motile stage
Sponge lack of tissue - CORRECT ANSWER - •Sponges lack tissues
-However, they do have specialized cells that perform specific functions.
, Every cell must be in contact with the environment
Cnidarians - CORRECT ANSWER - 1.Invertebrates with radial symmetry
2.Cells organized into tissues
3.Are marine predators
4.Mouth surrounded by tentacles
5.Uses stinging cells to capture food
6.Two distinct body forms
•Polyp (sea anemone)
•Medusa (jelly)
Include: sea anemones, hydras, corals, and jellies
Cnidarian Stinging- Nematocyst - CORRECT ANSWER - Nematocyst = stinging organelle
unique to cnidarians
help capture prey and deter predators
When trigger is touched, water diffuses into the capsule
Pressure builds up, the thread turns inside out, and the barbed tip pierces prey
Flatworms, Annelids, and Roundworms - CORRECT ANSWER - -Share similar body shape
-Different evolutionary heritage
Flatworms - CORRECT ANSWER - Lack digestive tract
1.Bilateral symmetry
2.Gastrovascular cavity
