Free Biodiversity and Variety of Life MCQs with Answers

1291. Enteron is the characteristic feature of:

• A. Phylum Porifera
• B. Phylum Cnidaria
• C. Phylum Platyhelminthes
• D. Phylum Echinodermata

Explanation: In cnidarians, there is only one cavity, which serves as a digestive as well as a body cavity, which is called the gastrovascular cavity or enteron.

1292. The body of which is called metamerically segmented?

• A. Cnidarians
• B. Nematodes
• C. Annelids
• D. Sponges

Explanation: The body of Annelids is called metamerically segmented. Annelids are a group of worms, including earthworms and leeches, that exhibit metamerism, which means their bodies are divided into a series of repeating segments or metameres. Each segment typically contains similar structures and can perform similar functions, such as locomotion using segmental muscles and housing specific internal organs. This segmentation is a characteristic feature of annelids and sets them apart from the other phyla listed.

1293. The green glands found in arthropods are concerned with:

• A. Excretion
• B. Respiration
• C. Digestion
• D. Circulation

Explanation: Option A is correct.The green glands found in arthropods are concerned with excretion. Green glands are paired excretory organs that are found in the head of crustaceans. They are responsible for filtering waste products from the blood and excreting them from the body. Green glands are also thought to play a role in osmoregulation, the process of maintaining a balance of water and salts in the body. The other options are not functions of the green glands:Respiration is the process of exchanging oxygen and carbon dioxide between the body and the environment. Arthropods respire through a variety of structures, including gills, tracheae, and book lungs. Digestion is the process of breaking down food into smaller molecules that can be absorbed by the body. Arthropods digest food in a variety of ways, including through their mouths, stomachs, and intestines.Circulation is the movement of blood throughout the body. Arthropods have an open circulatory system, in which the blood does not flow in closed vessels.

1294. In phylum Aschelminths (Nematoda) nervous system consists of a nerve ring which encircles the _ and sends its branches in different parts of the body

• A. Lips
• B. Teeth
• C. Stomach
• D. Pharynx

Explanation: Option D is correct.In phylum Aschelminths (Nematoda), the nervous system consists of a nerve ring which encircles the pharynx. The pharynx is a muscular tube that is located at the anterior (front) end of the nematode body. It is responsible for sucking in food and moving it to the digestive system. The nerve ring is a cluster of ganglia (nerve cell bodies) that encircles the pharynx. The nerve ring serves as a central nervous system for the nematode, and it sends nerve branches to all parts of the body. The other options are not parts of the nematode body that are encircled by the nerve ring: Lips are not present in nematodes.Teeth are not present in nematodes.The stomach is located in the posterior (back) end of the nematode body.

1295. Aquatic mammals belong to the order _

• A. Cetacea
• B. Pholidote
• C. Chiroptera
• D. Proboscidea

Explanation: Option A is correct.Aquatic mammals belong to the order Cetacea. Cetaceans are a group of marine mammals that includes whales, dolphins, and porpoises. They are characterized by their streamlined bodies, flippers, and lack of hind limbs. Cetaceans are also known for their intelligence and complex social behavior. The other options are orders of mammals that are not aquatic: Pholidota is the order of mammals that includes pangolins. Pangolins are scaly mammals that are found in Africa and Asia. Chiroptera is the order of mammals that includes bats. Bats are the only mammals that can fly. Proboscidea is the order of mammals that includes elephants. Elephants are the largest land mammals on Earth.

1296. Which of the following are animals with pointed ends and a tube like digestive track?

• A. Arthropods
• B. Annelids
• C. Nematodes
• D. Platyhelminthes

Explanation: Animals with pointed ends and a tube-like digestive tract are typically roundworms (phylum Nematoda)

1297. Class elasmobranch have an exoskeleton of

• A. Placoid scales
• B. Cycloid scales
• C. Ctenoid scales
• D. Ganoid scales

Explanation: This is the correct answer. Elasmobranchs, which include sharks, rays, and skates, have a unique type of exoskeleton called placoid scales. These scales are small, tooth-like structures embedded in the skin, providing protection and streamlining the body for swimming.

1298. The normal pH of blood is:

• A. 7.05
• B. 7.75
• C. 7.35
• D. 7.25

Explanation: The normal pH of human blood is slightly basic, around 7.35- 7.45. This pH is maintained by buffer systems like bicarbonate to ensure proper enzyme and metabolic function. A deviation can lead to acidosis or alkalosis, affecting body processes.

1299. The cells of the endoderm of Coelenterates are specialised for:

• A. Excretion
• B. Digestion
• C. Defense
• D. Respiration

Explanation: In Coelenterates (also known as Cnidarians), such as jellyfish, corals, and sea anemones, the endoderm (also known as the gastrodermis) is the innermost layer of cells that lines the digestive cavity. The cells of the endoderm are specialized for digestion, specifically:- Nutrient absorption- Enzyme secretion- Intracellular digestion (breaking down food particles within cells)The endoderm cells are responsible for:- Secreting digestive enzymes to break down food- Absorbing nutrients from the digested food- Eliminating waste products

1300. Parazoa are simple multicellular animals which are believed to have evolved from?

• A. Bacteria
• B. Protists
• C. Fungi
• D. Plants

Explanation: Parazoa is a subkingdom of animals that includes simple multicellular organisms, such as sponges (Phylum Porifera). They are believed to have evolved from protist ancestors, specifically from single-celled flagellated protists.Protists are a diverse group of eukaryotic microorganisms that don't fit into any of the traditional kingdoms (Animalia, Plantae, Fungi, or Monera). They share characteristics with animals, such as motility and heterotrophy (obtaining energy by consuming other organisms), but lack true tissues and organs.The evolutionary transition from protists to parazoans likely involved the development of:1. Multicellularity2. Cell differentiation3. Simple tissue organization