Free Biodiversity and Variety of Life MCQs with Answers

791. Aquatic reptiles are:

• A. Ureotelic
• B. Ureotelic in water
• C. Ammonotelic
• D. Ureotelic over land

Explanation: The waste material of aquatic reptiles chiefly consists of urea, so they are ureotelic. Land forms are uricotelic i.e., their water material consists of uric acid.

792. Temperature changes in the environment, affect most of the animals which are:

• A. Poikilothermic
• B. Homeothermic
• C. Aquatic
• D. Desert living

Explanation: Poikilothermic animals are those whose body temperature varies with the temperature of the environment. All animals except birds and mammals are poikilothermic. Although unable to maintain a constant body temperature, they can respond to compensate for very low or very high temperatures. For example, the tissue composition (especially cell osmotic pressure) can change to regulate the blood flow to peripheral tissues (and thus increase heat loss or heat absorption), and the animals can actively seek sun or shade.

793. Which of the following is not found in birds?

• A. Pelvic girdle
• B. Pectoral girdle
• C. Hindlimb
• D. Forelimb

Explanation: Forelimbs are absent in birds as they are modified into wings for flight. They are attached high on the back, to the anterior or thoracic region of the trunk, and are very powerful when compared with the size and strength of the bird. Each wing is elongated, flattened and distally pointed with its longitudinal axis at right angles to that of the trunk. The hindlimb is made of three parts i.e the thigh, shank and foot. The pectoral girdle on each side consists of three bones i.e a large coracoid, scapula and clavicle. The pelvic girdle consists of the ilium, ischium and pubis.

794. Which group of animals have long hollow bones that are connected by air passages?

• A. Reptilia
• B. Land vertebrates
• C. Aves
• D. Mammals

Explanation: Aves are flying animals with less body weight. Their bones are hollow and connected by air passages. Reptilia, land vertebrates and mammals do not have hollow bones.

795. Solenocytes are the main excretory structures in

• A. Echinodermates
• B. Platyhelminthes
• C. Annelids
• D. Molluscs

Explanation: Solenocytes are also called flame cells. They are cup shaped cells, which contain groups of cilia. They are the main excretory organs in platyhelminthes.

796. The lower jaw in mammals is made up of?

• A. Dentary
• B. Maxilla
• C. Angulars
• D. Mandible

Explanation: Dentary is a membrane bone, present in the lower jaw of the vertebrates, that supports the teeth. In mammals the dentary is the sole bone of the lower jaw. The dentary bone is a relatively short comma shaped bone.

797. Which one of the following cells found in the testes of rabbits secrete male hormones?

• A. Epithelial cells
• B. Spermatocytes
• C. Leydig's cell
• D. Sertoli cells

Explanation: The connective tissue in between the seminiferous tubules of the testis contains special interstitial cells or cells of Leydig. They secrete the male sex hormones (androgens) such as testosterone. This stimulates the secondary sexual characteristics of the male such as the enlargement of the external genitals and accessory glands.

798. What is common among silverfish, scorpion, crab and honey bee?

• A. Jointed legs
• B. Metamorphosis
• C. Compound eyes
• D. Poison glands

Explanation: Silver fish, scorpion, crab and honey bee all have compound eyes. These are present on each lateral side of the head and are convex. This eye consists of numerous visual units, the ommatidia. Each ommatidium consists of an outer cuticle covering a lens, beneath which are 68 retinal cells surrounding a light sensitive rhabdom. Adjacent ommatidia are separated by pigment cells.

799. The embryonated egg of Ascaris represents:

• A. An egg with blastula
• B. An egg with a juvenile
• C. An egg with an egg
• D. An egg with gastrula

Explanation: The embryonated egg of Ascaris represents an egg with a juvenile. In case of Ascaris, the eggs containing the second stage of juvenile are called embryonated eggs. These are infective to human hosts. In suitable conditions of temperature and moisture, these eggs can survive for 5 to 6 years in the soil.

800. Which of the following statements is without exception for sponges?

• A. They all have calcareous spicules
• B. They have high regenerative power
• C. They are found only in marine water
• D. They are all radially symmetrical

Explanation: Sponges may have calcareous or siliceous spicules. All sponges are not marine, some are freshwater living. Sponges may be asymmetrical or bilaterally symmetrical, besides being radially symmetrical. So, these characters are with exception. The character without exception is the regenerative power of sponges. All sponges have a good power of regeneration.They can egrow any part of the body lost or cut off. Small fragments can grow into a complete sponge.