QUESTION 1 The “Cambrian Explosion” describes the relatively sudden appearance of __________ in the fossil record in the Cambrian. Metazoans Eukaryotes Algae Cephalopods Chocolate 0.5 points QUESTION 2 Poriferans lack: Extracellular matrix Organs Choanocytes Nuclei 0.5 points QUESTION 3 Which of the following has no terrestrial species? Brachiopoda Nematoda Mollusca Arthropoda 0.5 points QUESTION 4 The metazoan phylum with the greatest diversity (i.e., number of species) today is: Arthropoda. Annelida. Cnidaria. Mollusca. 0.5 points QUESTION 5 Segmentation is a feature of: Cnidarians Platyhelminthes Nematodes Annelids 0.5 points QUESTION 6 A coelom is: Fun for the whole family. A fluid-filled body cavity forming within the mesoderm. A stinging cell found in cnidarians. A characteristic of flatworms. A fluid-filled body cavity between the mesoderm and endoderm. 0.5 points QUESTION 7 How old is the earliest fossil evidence of life? 3.8 Ma 3.8 Ga 1.8 Ga 543 Ma 0.5 points QUESTION 8 Which of the following is found only in bilaterians? Mesoderm Choanocytes Radial symmetry Gastrulation Nougat 0.5 points QUESTION 9 Which of the following is not an explanation put forward for the Cambrian Explosion? Oxygen increase Revolution in substrate use Predation Global warming 0.5 points QUESTION 10 Cnidarians are distinct from other animals in having: A can-do attitude Nematocysts Chitin Collagen Bilateral symmetry 0.5 points QUESTION 11 Which of the following is a group within Platyhelminthes? Insecta Velveeta Bivalvia Cestoda Hydrozoa 0.5 points QUESTION 12 Of Fungi, Metazoa, and Plantae, which two are thought to be more closely related to each other than they are to the third? Metazoa and Plantae Fungi and Plantae Fungi and Metazoa 0.5 points QUESTION 13 The Cryogenian is a period of the Proterozoic characterized by: Low self esteem Earliest fossils of life Cooling and glaciation Sudden appearance of fossils with hard parts Increase in oxygen 0.5 points QUESTION 14 Which of the following is thought not to have been abundant in the environment of the early Earth when life originated? Oxygen Nitrogen Methane Water 0.5 points QUESTION 15 Of Archaea, Bacteria, and Eukarya, which two are thought to be more closely related to each other than they are to the third? Bacteria and Eukarya Archaea and Bacteria Archaea and Eukarya 0.5 points QUESTION 16 The increase in oxygen that occurred around 2.3 Ga is referred to as: The Snowball Earth The Permian Extinction The Cambrian Explosion The Great Oxidation Event Friday 0.5 points QUESTION 17 A lophophore is: A feeding structure found in brachiopods and bryozoans. A reproductive structure found in annelids and molluscs. A photoautotroph. Available at Target™. Absent in all lophotrochozoans. 0.5 points QUESTION 18 One of the main divisions of protostomes is: Electronica Cnidaria Eukarya Lophotrochozoa Deuterostomia 0.5 points QUESTION 19 If, as some studies have suggested, Ctenophora is the sister-taxon to other metazoan.

1. QUESTION 1
The “Cambrian Explosion” describes the relatively sudden appearance of __________ in the
fossil record in the Cambrian.
Metazoans
Eukaryotes
Algae
Cephalopods
Chocolate
0.5 points
QUESTION 2
Poriferans lack:
Extracellular matrix
Organs
Choanocytes
Nuclei
0.5 points
QUESTION 3
Which of the following has no terrestrial species?
Brachiopoda
Nematoda
Mollusca
Arthropoda
0.5 points
QUESTION 4
The metazoan phylum with the greatest diversity (i.e., number of species) today is:
Arthropoda.
Annelida.
Cnidaria.
Mollusca.
0.5 points
QUESTION 5
Segmentation is a feature of:
Cnidarians
Platyhelminthes
Nematodes

2. Annelids
0.5 points
QUESTION 6
A coelom is:
Fun for the whole family.
A fluid-filled body cavity forming within the mesoderm.
A stinging cell found in cnidarians.
A characteristic of flatworms.
A fluid-filled body cavity between the mesoderm and endoderm.
0.5 points
QUESTION 7
How old is the earliest fossil evidence of life?
3.8 Ma
3.8 Ga
1.8 Ga
543 Ma
0.5 points
QUESTION 8
Which of the following is found only in bilaterians?
Mesoderm
Choanocytes
Radial symmetry
Gastrulation
Nougat
0.5 points
QUESTION 9
Which of the following is not an explanation put forward for the Cambrian Explosion?
Oxygen increase
Revolution in substrate use
Predation
Global warming
0.5 points
QUESTION 10
Cnidarians are distinct from other animals in having:
A can-do attitude
Nematocysts

3. Chitin
Collagen
Bilateral symmetry
0.5 points
QUESTION 11
Which of the following is a group within Platyhelminthes?
Insecta
Velveeta
Bivalvia
Cestoda
Hydrozoa
0.5 points
QUESTION 12
Of Fungi, Metazoa, and Plantae, which two are thought to be more closely related to each other
than they are to the third?
Metazoa and Plantae
Fungi and Plantae
Fungi and Metazoa
0.5 points
QUESTION 13
The Cryogenian is a period of the Proterozoic characterized by:
Low self esteem
Earliest fossils of life
Cooling and glaciation
Sudden appearance of fossils with hard parts
Increase in oxygen
0.5 points
QUESTION 14
Which of the following is thought not to have been abundant in the environment of the early
Earth when life originated?
Oxygen
Nitrogen
Methane
Water
0.5 points
QUESTION 15

4. Of Archaea, Bacteria, and Eukarya, which two are thought to be more closely related to each
other than they are to the third?
Bacteria and Eukarya
Archaea and Bacteria
Archaea and Eukarya
0.5 points
QUESTION 16
The increase in oxygen that occurred around 2.3 Ga is referred to as:
The Snowball Earth
The Permian Extinction
The Cambrian Explosion
The Great Oxidation Event
Friday
0.5 points
QUESTION 17
A lophophore is:
A feeding structure found in brachiopods and bryozoans.
A reproductive structure found in annelids and molluscs.
A photoautotroph.
Available at Target™.
Absent in all lophotrochozoans.
0.5 points
QUESTION 18
One of the main divisions of protostomes is:
Electronica
Cnidaria
Eukarya
Lophotrochozoa
Deuterostomia
0.5 points
QUESTION 19
If, as some studies have suggested, Ctenophora is the sister-taxon to other metazoans, this would
imply that:
Poriferans are not animals.
Cnidarians are not monophyletic.
We are all hosed.

5. Nervous systems evolved more than once, or were lost by Porifera.
Ctenophorans are cnidarians.
0.5 points
QUESTION 20
The chambered shells of fossil cephalopods contribute to:
Feeding.
The Red Cross.
Respiration.
Control of buoyancy.
Propulsion.
Metazoans
Eukaryotes
Algae
Cephalopods
Chocolate
Solution
Q 1. Metazoans. From phyligenetic ananlysis it was observed that during the Cambrian
explosion, metazoans (multi-celled animals) evolved monophyletically from a single common
ancestor, flagellated protists.
Q 2. Organs. Sponges lack organs and also tissue, and all the cells exhibit considerable
independence. The sponge is made up of two single-cell-deep layers and an intermediate
mesohyl (mobile cells plus extracellular matrix). The outer (sac) layer consists of flattened
polygonal cells called pinacocytes. The middle (mesohyl) layer consists of gelatinous
protein/carbohydrate material, and a skeleton of calcareous or siliceous spicules, or of elastic
proteinaceous fibers called spongin fibers. The inner layer consists of flagelled cells called collar
cells, or choanocytes.
Q 3. Brachiopoda has no terrestrial species, As Arthropoda, Nematoda and Mollusca 80 % of the
species are terrestrial species.
Q4. Arthropoda. Among invertebrates, arthropods (insects, crustaceans, spiders and relatives) are
by far the most diverse group with more than 1.2 million living species.
Q5. Annelida. Body elongate and composed of many segments, each segment with fine bristle
like setae for locomotion
Q6. A coelom is a fluid-filled body cavity that is completely lined by tissue created from the
mesoderm, the middle layer of the primary cells found in an embryo. It is typically found in

6. multicellular organisms, which are living things that have more than one cell.
Q7. 3.8Ga
Q8. Mesoderm
Q10. A can do attitude
Q11. Cestoda
Q12. Fungi and Plantae
Q15. Archea and Bacteria
Q17 A feeding structure found in brachiopods and bryozoans