Test: Zoology Mock Test - 4 - NEET MCQ

(II) Products of exorine glands are released through ducts or tubes.

A British scientist, J.B.S. Haldane, suggested that life originated from simple inorganic molecules. Two scientists, Stanley Miller and Harold Urey were the first to put to test, the Oparin - Haldane theory, in the year 1953. They created a condition similar to that of primitive earth (i.e. high temperature, volcanic storms, reducing atmosphere) containing ammonia (NH₃), water vapour (H₂O), hydrogen (H,), methane (CH₄). They made electric discharge in a closed flask containing CH₄, NH₃, H₂ and water vapour at 800° C. As a result, some amino acids are formed.

The primitive atmosphere was reducing due to lack of free molecular oxygen. The early atmosphere contained ammonia (NH₃), water vapour (H₂O), hydrogen (H₂), methane (CH₄).

The analogous organs are different in origin or basic plan, but have similar functions or adaptations. Wings ofbutterfly and wings of bird and fins of fishes and flippers of whale are some of the examples of analogous organs.

Diatoms are the most common form of phytoplankton in the ocean. They have the pigment chlorophyll which helps in photosynthesis.
Since, they are the primary producers of the aquatic food chain and the marine ecosystem depends on them. They are called chief producers in the oceans.

Leydig (interstitial) cells in the inter-tubular spaces are stimulated to secrete male sex hormone called androgens (mainly testosterone), under the influence of ICSH of anterior pituitary.

Deficiency of ADH (vasopressin) causes diabetes insipidus (increased volume of urine). It is caused due to decreased reabsorption of water from collecting tubules.

Melanocyte Stimulating Hormone (MSH) is secreted by pars intermedia. MSH acts on melanocytes to regulate pigmentation of skin.

Gonadotropin-releasing hormone (GnRH) is released from the anterior pituitary. GnRH activity is very low during childhood, and is activated at puberty or adolescence. At the puberty increased secretion of GnRH start the process of sperm formation.

The immature male germ cells or primary spermatocyte duplicate s its DNA and subsequently undergoes meiosis I which is a reductional division to produce two haploid secondary spermatocytes.

Oparin and Haldane of England proposed that the first form of life come from pre-existing nonliving molecules (eg, RNA, protein etc. and that formation of life was preceded by chemical evolution i.e. formation of diverse organic molecule from inorganic molecules.

Cells of smooth muscle tissue are spindle shaped and pointed at their ends. Striations are absent due to different arrangement of actin and myosin filaments. Smooth muscle is the earliest form of muscle to evolve.

Roundworms exhibit bilateral symmetry, which means that their bodies can be divided into two identical halves along a single plane. This characteristic symmetry allows for a clear front and back as well as a top and bottom, aiding in their movement and sensory perception.

Cardiac muscles are involuntary, cross striated & non-fatigued fibres. Cell junctions fuse the plasma membranes of cardiac muscle cells and make them stick together. Communication junctions (intercalated discs) at some fusion points allow the cells to contract as a unit, i.e., when one cell receives a signal to contract, its neighbouring cells are also stimulated to contract.

Diatoms are marine or freshwater unicellular organisms which have cell walls  composed of pectin impregnated with silica and consisting of two halves, one overlapping the other. The siliceous frustules of diatoms do not decay easily.

Each primary spermatocyte duplicates its DNA and subsequently undergoes meiosis I to produce two equal, haploid secondary spermatocytes. Each of the two secondary spermatocytes further undergoes meiosis II to produce two haploid spermatids.
Therefore, total four equal, haploid spermatids are producted after second meiotic division.

Smooth muscle is an involuntary, spindle shaped, uninucleated, tapering and non-striated muscle. Smooth muscle is responsible for the contractility of hollow organs, such as blood vessels, the gastrointestinal tract, the bladder, or the uterus. Its structure differs greatly from that of skeletal muscle, although it can develop isometric force per cross sectional area which is equal to that of skeletal muscle.

Hormones that interact with membrane-bound receptors do not enter the target cell directly but instead generate second messengers, such as cyclic AMP, IP3, or calcium, which then regulate cellular metabolism. This process allows for rapid and widespread cellular responses to hormonal signals.

Secretion of estrogen is stimulated by FSH of anterior pituitary gland.

All prokaryotic organisms come under Kingdom Monera. Escherichia coli is a bacterium. Monera includes bacteria, mycoplasmas, cyanobacteria (blue green algae) and actinomycetes.