Free Biodiversity and Variety of Life MCQs with Answers

2751. A fluid filled cavity which is mesodermal in origin but absent in nematodes is:

• A. Coelom
• B. Gastrocoel
• C. Pseudocoelom
• D. Spongocoel

Explanation: The coelom is a true body cavity that is entirely lined by mesodermal tissue, providing space for the development and suspension of organs. Nematodes, however, are classified as pseudocoelomates, meaning their body cavity is not completely lined by mesoderm. This distinguishes them from coelomates, which have a fully mesoderm-lined cavity. Other options like the gastrocoel and spongocoel refer to different types of cavities unrelated to the mesodermal origin, while the pseudocoelom, although a body cavity, lacks a complete mesodermal lining and is present in nematodes.

2752. Spiral and determinate type cleavage is present in:

• A. Pinworm
• B. Starfish
• C. Cake urchin
• D. Amphioxus

Explanation: Spiral and determinate cleavage is a feature of protostomes, a group that includes organisms such as annelids, mollusks, and nematodes. Pinworms, being nematodes, fall into this category and exhibit this type of embryonic development. In contrast, starfish, cake urchins, and amphioxus are deuterostomes, which are characterized by radial and indeterminate cleavage. This fundamental difference in early developmental stages is key to differentiating between these two major groups of animals.

2753. It is not true for Phylum Platyhelminthes:

• A. Bilaterally symmetrical
• B. Triploblastic metazoan
• C. Dorsoventrally compressed body
• D. Radially symmetrical body

Explanation: The correct answer is 'Radially symmetrical body'. Phylum Platyhelminthes is characterized by bilateral symmetry, meaning there is only one plane of symmetry that divides the body into left and right halves. In contrast, radial symmetry, which is incorrect for this phylum, involves multiple planes of symmetry that pass through a central axis, as seen in organisms like cnidarians. Additionally, Platyhelminthes are triploblastic metazoans with a dorsoventrally compressed body, which further distinguishes them from radially symmetrical organisms.

2754. Platyhelminthes means:

• A. Flat worms
• B. Roundworms
• C. Segmented worms
• D. None

Explanation: Word Platyhelminthes (derived from the Greek platy, meaning "flat" while helminth meaning "worm") are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates.

2755. In_both ovaries and oviducts are functional.

• A. Robin
• B. Kestrel
• C. Eagle
• D. Kiwi

Explanation: The kiwi is the best-known example of a bird in which both ovaries are functional.Kiwis are primitive, flightless birds (ratites), and they retain this ancestral condition.

2756. Proglottids are present in:

• A. Dugesia
• B. Schistostoma
• C. Fasciola
• D. Taenia

Explanation: Taenia: Has proglottids. Taenia is a type of tapeworm, and proglottids are segments of its body containing reproductive organs.

2757. The survival of an animal depends upon its ability to take some_from enviroment?

• A. Hydrocarbons
• B. Organic molecules
• C. Chemicals
• D. All of these

Explanation: An animal's survival does depend on its ability to take chemicals from the environment. An organism obtains the chemicals necessary for its survival from the environment.These chemicals include:Water: Water is essential for all life. It is used for a variety of purposes, including transporting nutrients, removing wastes, and regulating body temperature.Food: Animals need food to provide them with energy and the nutrients they need to grow and reproduce. Food can be obtained from plants, animals, or other sources.Oxygen: Oxygen is essential for cellular respiration, the process by which cells produce energy. Oxygen can be obtained from the air or from water.Other chemicals: Animals also need other chemicals, such as minerals, vitamins, and hormones, for their survival. These chemicals can be obtained from the food they eat, the water they drink, or the air they breathe.

2758. The organs of locomotion in annelids are which of the following?

• A. Muscle tissues
• B. Hydrostatic skeleton
• C. Parapodia
• D. Bones

Explanation: The locomotory organs in annelids include parapodia, suckers, and setae. Annelids are segmented worms that belong to the phylum Annelida. Their movement depends on special structures that help them crawl, burrow, or swim. According to the textbook, the organs of locomotion in annelids include parapodia, suckers, and setae. Parapodia are paired, fleshy, paddle-like structures found mainly in marine annelids such as polychaetes. They assist in crawling on the sea floor and also help in swimming. Each parapodium often contains many bristles called setae, which provide grip and support during movement. For annelids that do not have parapodia, such as earthworms, setae alone help them anchor different segments to the ground while their muscles push the body forward.

2759. All of the following are true for platyhelminthes except?

• A. Triploblastic
• B. Bilateral Symmetry
• C. Coelomate
• D. Flatworms

Explanation: Platyhelminthes are not coelomates; instead, they are acoelomates. They lack a true body cavity between the body wall and the digestive tract. Their internal spaces are filled with mesenchyme, which limits organ specialization compared to higher groups. Because this statement claims they are coelomate, it is false and is the correct exception.

2760. The sponges in which sperms develop first are included in the category of?

• A. Peritandrous
• B. Pertandrous
• C. Protonema
• D. Protandrous

Explanation: Protandry is a reproductive strategy where an organism starts as a male and later becomes a female. In the context of sponges, which are hermaphroditic (possessing both male and female reproductive organs), protandry refers to the fact that sponges initially produce and release sperm before transitioning to producing eggs.