Molluscs

Question 1

What is the primary characteristic that distinguishes Phylum Porifera from other animal phyla?

Answer 1

Porifera are characterized by their porous bodies and lack of true tissues.

Question 2

True or False: Sponges are primarily marine organisms.

Answer 2

True

Question 3

What type of symmetry do most sponges exhibit?

Answer 3

Most sponges exhibit asymmetry.

Question 4

Fill in the blank: The structural framework of sponges is composed of __________.

Answer 4

spicules or spongin

Question 5

Name the three main classes of sponges.

Answer 5

Calcarea, Hexactinellida, and Demospongiae.

Question 6

Which class of sponges includes the glass sponges?

Answer 6

Hexactinellida

Question 7

What type of feeding mechanism do sponges use?

Answer 7

Sponges are filter feeders.

Question 8

True or False: Sponges have a nervous system.

Answer 8

False

Question 9

Describe the role of choanocytes in sponges.

Answer 9

Choanocytes help in water circulation and food capture.

Question 10

What is the term for the cavity within a sponge where water flows?

Answer 10

The spongocoel.

Question 11

How do sponges reproduce asexually?

Answer 11

Sponges can reproduce asexually through budding or fragmentation.

Question 12

In which class of sponges are the majority of species found?

Answer 12

Demospongiae

Question 13

What is the life cycle stage of schyphozoans that is typically sessile?

Answer 13

The polyp stage.

Question 14

True or False: Schyphozoans are known for their dominant medusa stage.

Answer 14

True

Question 15

What is the primary mode of locomotion for adult schyphozoans?

Answer 15

Adult schyphozoans use pulsations of their bell to swim.

Question 16

Fill in the blank: The larval stage of schyphozoans is called a __________.

Answer 16

planula

Question 17

What is the primary purpose of nematocysts in schyphozoans?

Answer 17

Nematocysts are used for capturing prey and defense.

Question 18

Describe the process of strobilation in schyphozoans.

Answer 18

Strobilation is the process where the polyp produces multiple medusa buds.

Question 19

What is the ecological role of sponges in marine environments?

Answer 19

Sponges help filter water and provide habitat for other organisms.

Question 20

Which class of sponges can have a skeleton made of calcium carbonate?

Answer 20

Calcarea

Question 21

True or False: Schyphozoans are a type of cnidarian.

Answer 21

True

Question 22

What is the main characteristic of the medusa stage in schyphozoans?

Answer 22

The medusa stage is typically bell-shaped and free-swimming.

Question 23

Name one adaptation that allows sponges to thrive in aquatic environments.

Answer 23

Sponges have a unique ability to filter large volumes of water.

Question 24

What type of reproduction do schyphozoans typically undergo?

Answer 24

Schyphozoans can reproduce both sexually and asexually.

Question 25

In the life cycle of schyphozoans, what follows the planula stage?

Answer 25

The planula settles and develops into a polyp.

Question 26

Fill in the blank: The jellyfish form of schyphozoans is known as the __________.

Answer 26

medusa

Question 27

What is the reproductive characteristic of cephalopods?

Answer 27

Sexes are separate, and juveniles hatch directly from eggs with no free-swimming larvae.

Question 28

What is a spermatophore?

Answer 28

A spermatophore is a packet of sperm removed by a male cephalopod and inserted into the female.

Question 29

How do cephalopods change color?

Answer 29

Color changes are effected by chromatophores, which are pigment cells.

Question 30

What mechanism do cephalopods use to escape predators?

Answer 30

They squirt water by jet propulsion and may release an inky substance into the water.

Question 31

What are the characteristics of cephalopod eyes?

Answer 31

Most cephalopods have complex eyes with cornea, lens, chambers, and retina.

Question 32

What type of circulatory system do cephalopods have?

Answer 32

Cephalopods have a closed circulatory system.

Question 33

How do cephalopods swim?

Answer 33

They swim by expelling water from the mantle cavity through a ventral funnel.

Question 34

What is the shell structure in squid?

Answer 34

The shell has been reduced to a small strip called the pen, which is enclosed in the mantle.

Question 35

What type of shell do cuttlefish possess?

Answer 35

Cuttlefish have a small curved shell that is completely enclosed by the mantle.

Question 36

How are nautilus shells made buoyant?

Answer 36

Nautilus shells are made buoyant by a series of gas chambers.

Question 37

What is the body plan of most mollusks?

Answer 37

Most mollusks have a muscular foot, visceral mass containing organ systems, and a mantle.

Question 38

What is the function of the radula in mollusks?

Answer 38

The radula is a rasping, tongue-like feeding structure used for scraping food.

Question 39

What are the four major classes of mollusks?

Answer 39

* Class Polyplacophora (chitons) * Class Gastropoda (snails & slugs) * Class Bivalvia (clams, mussels, oysters) * Class Cephalopoda (octopus & squid)

Question 40

What is the life cycle of many mollusks?

Answer 40

Many mollusks include a free swimming, ciliated larval stage called a trochophore.

Question 41

What is the mantle cavity?

Answer 41

The space between the mantle and the visceral mass, housing respiratory organs.

Question 42

What type of circulatory system do most mollusks have?

Answer 42

Many mollusks have an open circulatory system, while most cephalopods have a closed circulatory system.

Question 43

What are the feeding habits of most gastropods?

Answer 43

Most gastropods are herbivores, feeding by scraping off algae using the radula.

Question 44

What is the function of incurrent and excurrent siphons in bivalves?

Answer 44

They are used to pump water through the organism for gas exchange and filter feeding.

Question 45

What is the structure of bivalve shells?

Answer 45

Bivalves have two laterally compressed shells held together by a hinge ligament.

Question 46

How do bivalves locomote?

Answer 46

Bivalves move by extending the muscular foot; scallops swim by clapping their shells together.

Question 47

What is unique about the shell of a gastropod?

Answer 47

The shell of a gastropod is always one piece (univalve) and may be coiled or uncoiled.

Question 48

What is a characteristic of scallops?

Answer 48

Scallops have a row of small blue eyes along the mantle edge.

Question 49

What are some ecological impacts of mollusks?

Answer 49

Shipworms damage wood structures, terrestrial snails and slugs damage plants, and zebra mussels disrupt ecosystems.

Question 50

What is the primary function of the mantle in mollusks?

Answer 50

The mantle houses the gills and may secrete a protective shell over the visceral mass.

Question 51

Define 'dioecious' in the context of mollusks.

Answer 51

Dioecious means having separate sexes.

Question 52

True or False: Most gastropods are carnivores.

Answer 52

False