CBSE Class 10 Biology Mixed Topics Test Paper MCQs Set 17

Answer: (c) Both (a) and (b)

Explanation:
1. Fungi lack chlorophyll and feed saprophytically (or parasitically) on dead matter; their cell wall is mainly chitin, not cellulose alone.

Teacher's Note:
1. Chitin makes the fungal cell wall.
2. Both statements (a) and (b) are true.

Answer: (c) numerous

Explanation:
1. Hibiscus has many stamens joined by their filaments into a tube around the style.

Teacher's Note:
1. Such stamens are called monadelphous.
2. Count of floral parts is a common family character.

Answer: (a) 22 pairs of autosomes and one X chromosome

Explanation:
1. Turner's syndrome is 44 + X (45 chromosomes): 22 pairs of autosomes and a single X.

Teacher's Note:
1. Klinefelter's syndrome is XXY.
2. Write the chromosome count as 44 + XO.

Answer: (d) Erythroblastosis foetalis

Explanation:
1. Haemophilia and colour blindness are carried on the X chromosome. Erythroblastosis foetalis is due to Rh incompatibility between mother and foetus.

Teacher's Note:
1. Sex-linked traits show more often in males.
2. Rh factor is an autosomal blood-group trait.

Answer: (d) excretion

Explanation:
1. Nephridia are the excretory organs of the earthworm.

Teacher's Note:
1. They remove nitrogenous waste as urea.
2. Setae help in locomotion.

Answer: (a) glands on the body of the lac insect

Explanation:
1. Lac insects secrete a resin from glands on their body. It is scraped off and refined into shellac.

Teacher's Note:
1. Honey bee wax comes from abdominal glands.
2. Silk is secreted by labial glands of silkworms.

Answer: (b) E. coli

Explanation:
1. The human insulin gene is placed into the bacterium Escherichia coli, which makes insulin in large fermenters.

Teacher's Note:
1. Penicillium gives penicillin.
2. Genetic engineering uses bacteria as living factories.

Answer: (d) all of the above are correct

Explanation:
1. Traps, poison baits such as zinc phosphide and natural enemies like owls and cats can all control rodents.

Teacher's Note:
1. Use more than one method for best control.
2. Biological control uses natural predators.

Answer: (c) pasteurisation

Explanation:
1. In pasteurisation milk is heated to a moderate temperature for a set time and then cooled quickly, which kills disease germs without spoiling the milk.

Teacher's Note:
1. Canning is for solid food items.
2. Pasteurised milk is still kept cool.

Answer: (a) vitamin C

Explanation:
1. Vitamin C is water soluble and is destroyed by heat and air, so it is lost most during washing and cooking.

Teacher's Note:
1. Fat-soluble vitamins are more stable.
2. Cook vegetables briefly with little water.

Answer: (a) cretinism

Explanation:
1. Too little thyroxine in childhood stunts physical and mental growth, called cretinism. In adults it causes myxoedema.

Teacher's Note:
1. Acromegaly and gigantism come from growth hormone.
2. Remember the child and adult pair: cretinism and myxoedema.

Answer: (c) parasitic

Explanation:
1. Cuscuta (dodder) is a leafless climber that absorbs food from the host plant with haustoria.

Teacher's Note:
1. It has no chlorophyll.
2. It is a total stem parasite.

Answer: (b) spermatozoids

Explanation:
1. Antheridia are the male organs and they make motile spermatozoids (antherozoids) which are the male gametes. Archegonia are the female organs.

Teacher's Note:
1. Gametes are sex cells and organs make them.
2. Fern sperms swim in water to reach the egg.

Answer: (b) Tree form

Explanation:
1. Liverworts, mosses and hornworts are bryophytes. Tree ferns and trees are vascular plants.

Teacher's Note:
1. Bryophytes lack vascular tissue and stay small.
2. They need moisture for fertilisation.

Answer: (c) 2n

Explanation:
1. A zygote is formed by the union of two haploid gametes, so it is diploid (2n).

Teacher's Note:
1. This holds for all sexually reproducing plants.
2. Meiosis later brings back n.

Answer: (b) 14th segment

Explanation:
1. The single female genital pore lies on the ventral side of the 14th segment.

Teacher's Note:
1. The male pores are on the 18th segment.
2. Remember 14 for female and 18 for male.

Answer: (d) pancreas

Explanation:
1. Earthworm has a pharynx, oesophagus and gizzard, but has no pancreas; a pigeon has a pancreas that makes digestive enzymes.

Teacher's Note:
1. Earthworm digests with enzymes from the intestinal wall.
2. Compare the two canals part by part.

Answer: (b) glucose

Explanation:
1. All carbohydrates are finally digested to glucose, which is absorbed through the intestinal villi.

Teacher's Note:
1. Proteins end as amino acids.
2. This is true for all vertebrates.

Answer: (b) two auricles and two ventricles

Explanation:
1. Birds have a four-chambered heart with two auricles and two ventricles, so oxygenated and deoxygenated blood do not mix.

Teacher's Note:
1. Reptiles (except crocodiles) have incompletely divided ventricles.
2. Four chambers suit the high energy need of flight.