Sample Questions and Answers
Which of the following best describes the nervous system of annelids?
A) Simple nerve net
B) Centralized brain and ventral nerve cord
C) Lack of a nervous system
D) Nerve ring with radial branches
Answer: B) Centralized brain and ventral nerve cord
Explanation: Annelids, such as earthworms, have a centralized nervous system with a brain and a ventral nerve cord running along their body.
Which of the following is true of the digestive system of arthropods?
A) Simple gut with one opening
B) Complex gut with separate mouth and anus
C) They lack a digestive system
D) They absorb nutrients through their skin
Answer: B) Complex gut with separate mouth and anus
Explanation: Arthropods have a complex digestive system with a separate mouth and anus, allowing for more efficient processing of food.
What type of body cavity is found in nematodes?
A) True coelom
B) Pseudocoelom
C) No body cavity
D) A circulatory cavity
Answer: B) Pseudocoelom
Explanation: Nematodes have a pseudocoelom, which is a body cavity that is not entirely lined with mesodermal tissue.
In which of the following phyla do organisms have a hard, calcareous exoskeleton?
A) Cnidaria
B) Mollusca
C) Arthropoda
D) Echinodermata
Answer: D) Echinodermata
Explanation: Echinoderms, like sea stars and sea urchins, have a hard calcareous exoskeleton made of calcium carbonate.
What is the primary method of feeding in most filter-feeding invertebrates, such as clams?
A) Carnivorous predation
B) Absorption of nutrients through skin
C) Filtering small particles from water
D) Grazing on plant matter
Answer: C) Filtering small particles from water
Explanation: Many invertebrates, such as clams, filter feed by drawing in water and extracting plankton and other small particles for food.
Which of the following is a key characteristic of the phylum Annelida?
A) Lack of body segments
B) Presence of a true coelom
C) Radial symmetry
D) Exoskeleton made of chitin
Answer: B) Presence of a true coelom
Explanation: Annelids, such as earthworms, have a true coelom, which is a body cavity fully lined by mesoderm tissue, allowing for better internal structure and flexibility.
Which of the following classes in phylum Mollusca includes animals that use a siphon to expel water and move?
A) Gastropoda
B) Cephalopoda
C) Bivalvia
D) Polyplacophora
Answer: B) Cephalopoda
Explanation: Cephalopods, such as squids and octopuses, use a siphon to expel water for jet propulsion, allowing them to move quickly in the water.
What type of symmetry is exhibited by cnidarians in their adult stage?
A) Bilateral symmetry
B) Radial symmetry
C) Asymmetry
D) Spherical symmetry
Answer: B) Radial symmetry
Explanation: Cnidarians, such as jellyfish and sea anemones, exhibit radial symmetry, meaning their body parts are arranged symmetrically around a central axis.
Which of the following is the main function of the nephridia in annelids?
A) Gas exchange
B) Circulation
C) Excretion of metabolic waste
D) Reproduction
Answer: C) Excretion of metabolic waste
Explanation: Nephridia in annelids are excretory organs that help in the removal of metabolic waste products, particularly nitrogenous wastes.
What type of digestive system do most cnidarians possess?
A) Incomplete digestive system
B) Complete digestive system
C) A body cavity that functions as the digestive system
D) No digestive system
Answer: A) Incomplete digestive system
Explanation: Cnidarians have an incomplete digestive system, meaning they have one opening that serves both as the mouth and the anus.
Which of the following best describes the reproduction method in hydra (a cnidarian)?
A) External fertilization
B) Budding (asexual reproduction)
C) Binary fission
D) Internal fertilization
Answer: B) Budding (asexual reproduction)
Explanation: Hydra reproduce asexually by budding, where a new individual develops from an outgrowth of the parent organism.
Which of the following organisms is known for its ability to regenerate lost body parts?
A) Flatworms
B) Earthworms
C) Starfish
D) Squid
Answer: C) Starfish
Explanation: Starfish (echinoderms) have remarkable regenerative abilities, allowing them to regrow lost arms, and in some cases, an entire body from a single arm.
What is the primary function of the parapodia in polychaete annelids?
A) Reproduction
B) Locomotion and gas exchange
C) Excretion
D) Digestion
Answer: B) Locomotion and gas exchange
Explanation: Parapodia are paired, paddle-like appendages found in polychaete annelids that aid in locomotion and facilitate gas exchange.
Which of the following is a characteristic of the phylum Arthropoda?
A) Lack of a circulatory system
B) Segmented body with jointed appendages
C) Presence of a dorsal nerve cord
D) Soft, unsegmented body
Answer: B) Segmented body with jointed appendages
Explanation: Arthropods have a segmented body with jointed appendages, which is a key feature of this phylum, including insects, spiders, and crustaceans.
Which of the following describes the circulatory system of most arthropods?
A) Closed circulatory system
B) Open circulatory system
C) No circulatory system
D) A network of capillaries
Answer: B) Open circulatory system
Explanation: Most arthropods have an open circulatory system, where the blood is not confined to blood vessels but rather flows freely in body cavities.
Which of the following structures do mollusks use for movement?
A) Tentacles
B) Foot
C) Wings
D) Antennae
Answer: B) Foot
Explanation: Mollusks use their muscular foot for locomotion. In some species, the foot is modified for burrowing, swimming, or crawling.
What is the primary function of the mantle in mollusks?
A) Digestion
B) Protection and secretion of the shell
C) Reproduction
D) Respiration
Answer: B) Protection and secretion of the shell
Explanation: The mantle in mollusks is responsible for secreting the shell in species that have one and also provides protection to the internal organs.
Which of the following is a characteristic feature of echinoderms?
A) Bilateral symmetry in adults
B) A water vascular system
C) Exoskeleton made of chitin
D) Lack of a nervous system
Answer: B) A water vascular system
Explanation: Echinoderms, such as sea stars and sea urchins, possess a unique water vascular system used for locomotion, feeding, and gas exchange.
Which of the following is true of the circulatory system in most mollusks?
A) They have a closed circulatory system with blood vessels
B) They have an open circulatory system with hemolymph
C) They have no circulatory system
D) Their circulatory system is entirely external
Answer: B) They have an open circulatory system with hemolymph
Explanation: Most mollusks have an open circulatory system, where the blood is not contained in vessels but circulates through body cavities in the form of hemolymph.
In which class of phylum Mollusca are snails and slugs classified?
A) Bivalvia
B) Gastropoda
C) Cephalopoda
D) Polyplacophora
Answer: B) Gastropoda
Explanation: Snails and slugs belong to the class Gastropoda, which includes animals that typically have a single coiled shell or are shell-less.
Which of the following groups of animals is known for its soft, unsegmented body and often a calcareous shell?
A) Annelids
B) Mollusks
C) Arthropods
D) Echinoderms
Answer: B) Mollusks
Explanation: Mollusks are known for their soft, unsegmented body, and many possess a calcareous shell made of calcium carbonate, such as in snails and clams.
What is the primary function of the radula in mollusks?
A) Respiration
B) Movement
C) Digestion and feeding
D) Excretion
Answer: C) Digestion and feeding
Explanation: The radula is a specialized feeding structure in many mollusks, particularly gastropods, that scrapes or cuts food, especially algae or plant material.
Which of the following organisms is known for having a complex brain and eyes that are capable of forming images?
A) Clams
B) Sea stars
C) Octopuses
D) Jellyfish
Answer: C) Octopuses
Explanation: Octopuses, a type of cephalopod mollusk, are known for their advanced intelligence and complex nervous system, which includes highly developed eyes capable of forming images.
Which of the following is true about the phylum Nematoda?
A) Nematodes are characterized by a segmented body.
B) Nematodes have a complete digestive system.
C) Nematodes lack a digestive system.
D) Nematodes are radially symmetrical.
Answer: B) Nematodes have a complete digestive system
Explanation: Nematodes (roundworms) have a complete digestive system with two openings, a mouth and an anus, allowing for more efficient digestion.
Which of the following is true regarding the exoskeleton of arthropods?
A) It is made of chitin and provides support, protection, and prevents water loss.
B) It is made of calcium carbonate and allows for flexibility.
C) It is made of collagen and aids in nutrient absorption.
D) It is soft and can grow continuously.
Answer: A) It is made of chitin and provides support, protection, and prevents water loss
Explanation: Arthropods possess an exoskeleton made of chitin, which provides support, protection, and helps prevent water loss, crucial for survival in various environments.
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