Free Biodiversity and Variety of Life MCQs with Answers

861. What external changes are visible after the last moult of a cockroach nymph?

• A. Both forewings and hindwings develop
• B. Labium
• C. Mandibles become harder
• D. Anal cerci

Explanation: Cockroaches undergo paurometabolous development. The nymph moults about 67 times to reach the adult form. The next to last nymphal stage has wing pads but only adult cockroaches have wings.

862. Select the correct option with respect to cockroaches.

• A. Malpighian tubules convert nitrogenous wastes into urea
• B. Males bear short anal styles not present in females
• C. Nervous system comprises of a dorsal nerve cord and ten pairs of ganglia
• D. The forewings are tegmina which are used in flight

Explanation: Males have paired anal styles on 9th abdominal sternite which are absent in females.

863. One very special feature in the earthworm (Pheretima) is that:

• A. Fertilization of eggs occurs inside the body
• B. The typhlosole greatly increases the effective absorption area of the digested food in the intestine
• C. The S-shaped setae embedded in the integument are the defensive weapons used against the enemies
• D. It has a long dorsal tubular heart

Explanation: In Pheretima, the intestine is next to the stomach. It is a long, wide and thin-walled tube extending from the 15th segment to the last. The second or middle part of the intestine lies between the 27th segment up to the 23-25th segments in front of the anus. This is characterised by the presence of a highly glandular and vascular longitudinal ridge, arising as a median ingrowth of the dorsal aspect of the intestinal cavity. This is called the typhlosole. The typhlosole greatly increases the effective absorption area of the digested food in the intestine.

864. Which of the following happens is true about the common cockroach?

• A. Malpighian tubules are its excretory organs projecting out from the colon
• B. Oxygen is transported by haemoglobin in their blood
• C. Its nitrogenous excretory product is urea
• D. Their food is ground by mandibles and the gizzard

Explanation: The mouth part of the cockroach contains two mandibles. When both the mandibles work simultaneously in the horizontal plane, the food matter is cut and masticated into fine and smaller pieces. The gizzard is a part of the alimentary canal. It bears six muscular folds which are covered by chitinous conical plates, the teeth, used for grinding the food.

865. Frogs differ from humans because they possess:

• A. Paired cerebral hemispheres
• B. A hepatic portal system
• C. Nucleated red blood cells
• D. A thyroid as well as parathyroid

Explanation: Human erythrocytes are enucleated and discoidal while in frogs erythrocytes are large, oval and biconvex nucleated cells. Erythrocytes are the carriers of haemoglobin.

866. Which one of the following structures in Pheretima is correctly matched with its function?

• A. Clitellum - Secretes cocoon
• B. Gizzard - Absorbs digested food
• C. Setae - Defence against predators
• D. Typhlosole - Storage of extra nutrients

Explanation: In a mature earthworm, the 14th and 16th segments are covered by a prominent dark band of glandular tissues called clitellum which secretes cocoon where fertilization and development takes place. In alimentary canal,the muscular gizzard (8th and 9th segments) helps in grinding the soil particles and decaying leaves. The characteristic feature of the intestine between 26th and 35th segments is the presence of an internal median fold of dorsal wall called typhlosole. This increases the effective area of absorption in the intestine. In each body segment, except the first, last and clitellum, there are rows of S shaped setae, embedded in the epidermal pits in the middle of each segment. Setae can be extended or retracted. Their principal role is in locomotion.

867. The kind of tissue that forms the supportive structure in our pinna(external ears) is also found in:

• A. Nails
• B. Ear ossicles
• C. Tip of the nose
• D. Vertebrae

Explanation: Yellow elastic fibrocartilage, a type of skeletal tissue, is found in the pinna, Eustachian tubes, epiglottis and tip of the nose. It is a type of cartilage and due to presence of yellow fibres, it becomes more flexible.

868. Earthworms have no skeleton but during burrowing, the anterior end becomes turgid and acts as a hydraulic skeleton.This is due to:

• A. Gut peristalsis
• B. Setae
• C. Coelomic fluid
• D. Blood

Explanation: The hydraulic skeleton is the system of support found in soft-bodied invertebrates which relies on the incompressibility of fluids contained within the body cavity. In earthworms the coelomic fluid is under pressure within the coelom and therefore provides support for internal organs. Due to the hydraulic skeleton, during burrowing, the anterior end becomes turgid and aids in the relaxation of longitudinal muscles.

869. Which one of the following is the true description about an animal concerned?

• A. Rat: Left kidney is slightly higher in position than the right one
• B. Cockroach: 10 pairs of spiracles(2 pairs on thorax and 8 pairs on abdomen)
• C. Earthworm: The alimentary canal consists of a sequence of pharynx, oesophagus, stomach, gizzard and intestine.
• D. Frog: Body divisible into three regions: head, neck and trunk.

Explanation: There are 10 pairs of spiracles in cockroach. Two pairs are thoracic in which first pair is known as mesothoracic, lying infront of the mesothorax between the bases of first and second pair of legs and are the largest. The second pair is called metathoracic. Abdominal spiracles are eight pairs. The first pair is dorsal in position and lies on the lateral margins of the first abdominal tergum. The remaining are situated on the sides of their corresponding segments on the pleura between the terga and sterna. Spiracles are meant for intake of fresh air and release of foul air.

870. The blood of Pheretima is:

• A. Blue with haemocyanin in corpuscles
• B. Blue with haemocyanin in plasma
• C. Red with haemoglobin in corpuscles
• D. Red with haemoglobin in plasma

Explanation: The circulatory or blood vascular system of earthworm is a closed system consisting of blood vessels and capillaries which ramify all parts of the body. Blood is composed of fluid plasma and colourless corpuscles, physiologically comparable to the leucocytes of the vertebrates. The red respiratory pigment, haemoglobin (or erythrocruorin) occurs dissolved in plasma. It gives a red colour to blood and aids in the transportation of oxygen for respiration.