All Free Biology MCQs with Answers

2031. How many vertebrae are present in vertebral column of man?

• A. 33 vertebrae
• B. 33 pairs of vertebrae
• C. 25 vertebrae
• D. 31 vertebrae

Explanation: The human vertebral column has 33 vertebrae in the early developmental or standard anatomical count, although some later fuse to form the sacrum and coccyx. The likely distractor is 33 pairs, because vertebrae are counted individually rather than as paired bones.

2032. Which of the following bones bones are present in the plam of hand?

• A. Carpals
• B. Metacarpals
• C. Phalanges
• D. Metatarsals

Explanation: The metacarpals are the five long bones forming the palm between the wrist and fingers. The likely distractor is carpals, which are the eight small bones of the wrist, while phalanges form the fingers.

2033. How many bones are present in the wrist?

• A. 4 bones
• B. 6 bones
• C. 8 bones
• D. 14 bones

Explanation: The wrist contains 8 carpal bones arranged in two rows of four. The likely distractor is 14, which is the total number of finger bones in both hands only if counting both hands, not the bones in one wrist.

2034. Which of the following bone is not present in the hind-limb?

• A. Femur
• B. Tibia
• C. Radius
• D. Fibula

Explanation: The radius is a bone of the forearm and is not part of the hind limb. The femur, tibia and fibula are all major bones of the hind limb, so they are not suitable choices.

2035. Collagen fibers of bone are hardened by deposition of_____________?

• A. Ca & PO4
• B. CaCO3
• C. CaSO4
• D. SiO2

Explanation: Bone collagen is hardened mainly by deposition of calcium phosphate, represented here as Ca and PO4, which forms mineral crystals in the matrix. The likely distractor is calcium carbonate, but calcium phosphate is the principal mineral salt responsible for bone hardness.

2036. Endoskeleton is secreted by?

• A. Ectoderm.
• B. Endoderm.
• C. Mesoderm.
• D. All of these

Explanation: The endoskeleton develops mainly from mesoderm, the embryonic germ layer that gives rise to connective tissues, cartilage and bone. The likely distractor is ectoderm, which forms structures such as the epidermis and nervous system rather than the internal skeleton.

2037. Ecdysone is_________________?

• A. An enzyme that digest endocuticle during an arthropodal ecdysis
• B. A newly formed exoskeleton in authropods
• C. A hormone that regulates moulting in arthropods
• D. A process that involves moulting

Explanation: Ecdysone is a hormone produced by arthropods that initiates and regulates moulting by promoting changes in the old cuticle and development of a new one. The likely distractor is an enzyme digesting the endocuticle, but that is an enzymatic process associated with moulting, not the identity of ecdysone.

2038. Exoskeleton of a marine snail is composed of________________?

• A. CaPO4
• B. CaCO3
• C. CaSO4
• D. SiO2

Explanation: A marine snail's shell is mainly calcium carbonate, CaCO3, deposited by the mantle as the shell grows. Calcium phosphate is associated mainly with vertebrate bones, so students may select CaPO4 by confusing a shell with an internal bony skeleton.

2039. Which one of the following forms the blk of exoskeleton of an arthropod?

• A. Epicuticle
• B. Procuticle
• C. Ectocuticle
• D. None of these

Explanation: The procuticle forms the main bulk of an arthropod's exoskeleton and contains the tough exocuticle and more flexible endocuticle. Students may choose epicuticle because it is the outermost layer, but it is a thin covering rather than the bulk of the exoskeleton.

2040. Which of the following statement is incorrect about Molluscans?

• A. They are surrounded by single or double pieces of hard skeleton.
• B. Their shell grows as the animal grows.
• C. They have hydrostatic skeleton.
• D. They move by tube feet

Explanation: Molluscs may have a shell, their shell grows with the animal, and their soft bodies can use a fluid-supported hydrostatic skeleton. Tube feet are characteristic of echinoderms such as starfish, not molluscs, so d is incorrect.