Question

1) The disappearance of a physical trait of white flowers in a cross of purebred pea plants, but reappearance in the F2 generation illustrates Mendel's Law of

            a)segregation   b)mass action   c)thermodynamics   d)independent assortment

2) The insulating layers around nerve fibers are composed primarily of

     a)myosin b)myelin c)triglyceride d)cholesterol

3) All of the following are tropic hormones except a)FSH   b)prolactin c)ADH d)ACTH

4) The thin filaments of striated muscle are made of the protein

      a)actin b)myosin c)tropomyosin d)tubulin

5) The thick filaments of striated muscle are made of the protein

Answer 1

1) Segregation

Factors controlling various traits exist in pairs. Pairs segregate at the time of gamete formation and recombine during fertilisation. During the monohybrid cross Mendel observed that white flowers disappeared during the F1 generation due to dominant effect of the other allele but reappeared during the F2 because alleles don't blend in the hybrid and segregate at the time of gametes formation.

2) Myelin

Insulating layer around the axons in myelinated neurons is made up of myelin. Myelin is secreted by the Schwann cells in the peripheral nervous system and by the oligodendrocytes in the central nervous system. Myelin increases the speed of nerve impulse conduction.

3) ADH

ADH or Antidiuretic hormone is not a tropic hormone it targets kidneys and blood vessels. ADH is released by the posterior pituitary.

Tropic hormones are those hormones which target other endocrine glands. Most tropic hormones are secreted by the anterior pituitary.

FSH or follicles stimulant is hormone targets gonads.

ACTH or Adrenocortico tropic hormone targets adrenal glands.

Prolactin targets mammary glands.

4) Actin

Thin filament of striated muscle fibre is made up of protein actin.

5) Myosin

Thick filament of striated muscle fibre is made up of protein myosin.