CBSE Questions for Class 9 Biology Diversity In Living Organisms Quiz 2 - MCQExams.com

• All females of the class Mammalia have mammary glands. The glands produce milk after the birth of offspring. Milk is a nutritious fluid. It contains disease-fighting molecules as well as all the nutrients a baby mammal needs. Producing milk for offspring is called lactation.
• Most mammals give birth to live young, but a few (the monotremes) lay eggs.
• Mammals can be both herbivorous and carnivorous. 

• Petromyzon (Lamprey) and Myxine (Hagfish) both belong to the class Cyclostomata.
• Cyclostomes are jawless vertebrates. They are characterized by having an elongated eel-like body, circular mouth, slimy skin and are scaleless. 

• The lateral line system is an aquatic adaptation that helps aquatic animals to detect vibrations and movements in the water. 
• It is absent in terrestrial vertebrates like reptiles, frogs, and men.

• Balanoglossus is a marine worm belonging to phylum Hemichordata. Hemichordata was earlier considered as a subphylum under phylum Chordata. But now it is placed as a separate phylum.
• They share characteristics with both echinoderms and chordates. Their adult morphology resembles that of a chordate, while many traits in their larva resemble echinoderms.
  
• Archaeopteryx is a fossil bird showing both reptile and bird characters.
• Peripatus is an invertebrate and connecting link between the Annelida, or segmented worms, and the Arthropoda.
• Asterias (Starfish) belong to the phylum Echinodermata.

• Fishes are classified into two groups: Chondrichthyes (cartilaginous endoskeleton) and Osteichthyes (bony endoskeleton). 
• Shark belongs to Chondrichthyes. They have a cartilaginous endoskeleton and paired nares. They are the jawed vertebrates with scales. 
• While Tuna and Rohu belong to Osteichthyes. 

Balanoglossus is a hemichordate acorn worm. It is the connecting link between invertebrates and vertebrates. It is basically a bottom-dwelling marine worm. It is tubicolous, that is, lives inside U-shaped burrows or tubes in the sand.  In Balanoglossus, the sexes are separate and prominent sexual dimorphism does not exist and fertilization is external, that is, it takes place outside the body of the organism.

• Animals of phylum Chordata are characterised by the presence of the notochord, a dorsal hollow nerve cord, post-anal tail and pharyngeal gill slits.
• In adult vertebrates, the notochord is replaced by the vertebral column.
• The diaphragm is a thin skeletal muscle found only in mammals.
• Amnion is present only in mammals, birds, and reptiles. It is the innermost membrane that encloses the embryo. 
• Thus, the correct answer is option D. 

• Most species of fungi are saprotrophic, they feed on decomposing and dead matter. 
• Some species are parasites and others are mutualistic. 
• Fungi are the principle decomposers in every ecosystem.
• Many are extremely beneficial, breaking down this organic material into humus, minerals, and nutrients that can be utilized by plants.