CBSE Questions for Class 11 Medical Biology Structural Organisation In Animals Quiz 11 - MCQExams.com

1. The various complex proteins involved in muscle contraction are actin and myosin along with troponin and tropomyosin.
2. Thyroid hormones are triiodothyronine (T3) and Tetraiodothyronine (T4) which help in regulating the Basal Metabolic Rate of the body.
3. Pepsin is a protein digestive enzymes secreted in the stomach but prolactin is a hormone secreted by the anterior pituitary.
4. Secretin is a polypeptide hormone which functions to regulate pH of the stomach by inhibiting gastric acid secretion but rhodopsin is the visual pigment present in our eyes and a G protein-coupled-receptor.

• The contractile regulatory proteins that mask and unmask active sites in the sarcomere are troponin and tropomyosin. 
  
• The two tropomyosin filaments run close to the actin filaments throughout its length.
  
• The troponin units are distributed throughout the length of tropomyosin filaments and mask the active binding sites for myosin.
  
• During muscle contraction, the increased calcium ion levels lead to their binding to a subunit of troponin and unmasking the active sites for myosin filaments.
  

• The bone is mainly composed of calcium and phosphorus. The bone is a hard connective tissue.

• In cockroaches, mandibles are a pair of short, triangular, hard, unjointed, chitinized structures present on either side of the mouth.
  
• The inner margins of mandibles have teeth-like structures that help to masticate food.
• The gizzard is the next structure that is present after the crop. It helps in grinding the food particles due to the presence of six chitinous plates called teeth.
• The Malpighian tubules perform the excretion in a cockroach. There are glandular and ciliated cells that are present lining each tubule, which absorb the nitrogenous waste products. These are found at the junction of the midgut and hindgut and is about 150 in number.
  
• The blood of cockroaches does not have haemoglobin or any other respiratory pigment to carry oxygen.
• Nitrogenous excretory product is uric acid.
  

• Bone is a kind of specialised connective tissue.
• They support and protect the various organs of the body, produce RBC's and WBC's, store minerals, provide structure and support for the body, and enable mobility.
  

The earthworm is invertebrates and as we know invertebrates lacks skeleton. So, the coelomic fluid present in coelomic chambers acts as a hydrostatic skeleton so that the structure is maintained. It is helpful in the contraction and relaxation of the muscles in the earthworm's body. 

So, the correct answer is option  is (A)

A small chamber in the respiratory system of cockroach, into which spiracles open is called atrium.

• Cardiac muscles : Branched, cylindrical, Involuntary, Uninucleated.
  
• Skeletal muscles : Unbranched, Cylindrical, Voluntary, Multinucleated.
  
• Smooth muscles : Fusiform, Involuntary, Uninucleated.
  

• In cockroach, mandibles are a pair of short, triangular, hard, unjointed,chitinised structures present on either side of the mouth.
• The inner margins of mandibles have teeth like structures. Each mandible has two types of teeth. They are incising teeth and grinding teeth. These teeth help to masticate food.
• Hence Mandibles of cockroach are short with grinding teeth.
• So, the correct answer is 'Short with grinding teeth'.

• Smooth muscle fibers are unstriated/ unstriped means with no striations. And they are located in walls of hollow visceral organs, except the heart, appear spindle-shaped, and are also under involuntary control. 
• Skeletal muscle fibers are present in muscles which are attached to the skeleton. They show striated appearance and are under voluntary control. 
• So, the correct answer is 'False'

• Each cardiac muscle has a single centrally located nucleus.
• Cardiac muscle cells are striated due to a similar arrangement of contractile proteins.
• They mainly function in the pumping of oxygen-rich blood throughout the body to provide cells with vital nutrients.
So, the correct option is 'They are connected by intercalated discs, through which action potential spread to all cells in the heart'.