Biology Test 374

The correct answer is a - iv, b - iii, c - ii, d - i

Explanation:

(a) 1971 - (iv) Viroids: Viroids were discovered in 1971 by Theodor Diener. These are infectious agents composed solely of a short strand of circular, single-stranded RNA without a protein coat, which is in contrast to viruses.

(b) 1969 - (iii) R.H. Whittaker: In 1969, Robert H. Whittaker proposed the five-kingdom classification system of living organisms, which includes Monera, Protista, Fungi, Plantae, and Animalia.

(c) 1892 - (ii) Dmitri Ivanowsky: In 1892, Dmitri Ivanowsky discovered that tobacco mosaic disease could be transmitted by an agent smaller than bacteria, which led to the identification of viruses.

(d) 1898 - (i) Infectious living fluid: In 1898, Martinus Beijerinck coined the term "virus" and described it as an infectious living fluid, furthering the understanding of viral diseases.

The correct answer is a-t, b-r, c-s, d-q

Explanation:

Hypothalamus (a) - Gonadotropin releasing hormone (t): The hypothalamus releases Gonadotropin releasing hormone (GnRH), which plays a crucial role in regulating the reproductive system by stimulating the anterior pituitary gland to release FSH and LH.

Anterior pituitary (b) - FSH and LH (r): The anterior pituitary gland releases Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH), which are essential for the regulation of the reproductive processes including ovulation and sperm production.

Testis (c) - Androgens (s): The testis primarily produces androgens, such as testosterone, which are crucial for male secondary sexual characteristics and spermatogenesis.

Ovary (d) - Estrogen (q): The ovary is responsible for producing estrogen, a hormone that is vital for the regulation of the female reproductive system and secondary sexual characteristics.

The correct answer is Rudolf Virchow

Explanation:

"Omnis cellula e cellula" is a Latin phrase that translates to "Every cell from a cell." This fundamental concept in cell theory was first articulated by Rudolf Virchow in 1855.

Rudolf Virchow was a German physician, pathologist, and anthropologist, Virchow is often referred to as the "Father of Modern Pathology."

He proposed that all cells arise from pre-existing cells

The correct answer is Columnar

Concept:

• Epithelial cells are a type of cell that lines the surfaces of your body.
• They are found on your skin, blood vessels, urinary tract, and organs. These cells serve as a barrier and protective layer, and they also have other functions depending on their location and type.
• The shape and arrangement of epithelial cells can vary, and they are classified into several types including squamous, cuboidal, and columnar based on their shape.

Explanation:

• Columnar: The columnar epithelium is composed of a single layer of tall and slender cells.
  • Their nuclei are located at the base.
  • Free surface may have microvilli.
  • They are found in the lining of stomach and intestine and help in secretion and absorption.
• Squamous: These cells are flat and thin, resembling the scales of a fish. The nucleus is usually centrally located and flattened. Squamous epithelial cells are found lining surfaces such as the skin, mouth, and esophagus.
• Cuboidal: These cells are as tall as they are wide, resembling a cube. The nucleus is centrally located and spherical. Cuboidal epithelial cells are found in glandular tissue and in the lining of kidney tubules.
• Upper layer of skin: The upper layer of skin is primarily composed of stratified squamous epithelium. In these cells, the nucleus is flattened and located centrally, not at the base.
• Ciliated: If the columnar or cuboidal cells bear cilia on their free surface they are called ciliated epithelium.
  • These cells are taller than they are wide, resembling a column.
  • The nucleus of columnar epithelial cells is typically elongated and located at the base of the cell.
  • These cells are found lining the stomach, intestines, and respiratory tract.

The correct answer is Lipo-protein molecules

Explanation:

• The plasma membrane, also known as the cell membrane, is a biological membrane that separates the interior of all cells from the external environment.
• It plays a vital role in maintaining the structural integrity of the cell, regulating the movement of substances in and out of the cell, and facilitating communication and signaling between cells.
• The plasma membrane is primarily composed of a lipid bilayer interspersed with proteins.

• S. Jonathan Singer and Garth Nicolson proposed the Fluid Mosaic Model in 1972.
• According to this model, the structure of the plasma membrane is a mosaic and is made up of lipids, proteins, cholesterol, and carbohydrates.
• Lipids are present in the form of two layers known as lipid bilayers with protein embedded in it.
• The major constituent of lipids is phospholipids. Each phospholipid is made up of a hydrophilic head and a hydrophobic tail.
• Two types of proteins present in the plasma membrane are peripheral proteins and integral proteins. Integral proteins are deeply embedded in the membrane as compared to the peripheral proteins.
• Cholesterol helps in retaining the fluidity of the membrane.

The correct option is 1. i.e. II only

• A cell contains mainly of a cell wall, plasma membrane, cell organelles and cytoplasm. Hence, statement I is wrong.
• Mycoplasma gallisepticum is the smallest cell in size.
• The cell membrane of human RBC is composed of 52% proteins and 48% lipids. Hence, statement III is wrong. Hence, statement III is wrong.
• Study of a cell is known as cytology. Hence, statement IV is wrong.
• Mycology is the study of fungi.

The correct answer is Both Statement I and Statement II are correct

Explanation:

• Blood pressure is the force exerted by circulating blood on the walls of blood vessels. It is typically measured in millimeters of mercury (mm Hg) and expressed as two values, systolic pressure over diastolic pressure.
• Chordae Tendinae are thread-like tendons that connect the papillary muscles to the tricuspid valve and mitral valve in the heart's ventricles. They play a crucial role in preventing valve prolapse during ventricular contraction.
  • Statement I: In an adult man, a normal blood pressure reading is typically around 120/80 mm Hg. The systolic pressure (120 mm Hg) represents the pressure when the heart beats and pumps blood, while the diastolic pressure (80 mm Hg) represents the pressure when the heart is at rest between beats.
  • Statement II: Chordae tendinae are present in the ventricles of the heart. They are crucial for the proper functioning of the heart valves, ensuring that the valves close tightly and do not invert during the contraction of the ventricles.

The correct answer is A-Arithmetic phase: B-Geometric phase

Explanation:

• Growth phases in a population refer to the patterns and rates at which growth occurs over time. Two common types are arithmetic (linear) growth and geometric (exponential) growth.
• Arithmetic growth occurs when a population increases by a constant amount per unit time. This results in a straight-line graph when plotted.
• Geometric growth occurs when a population increases by a constant proportion (percentage) per unit time. This results in a J-shaped curve when plotted.

The correct answer is Both assertion and reason are correct, and reason is the correct explanation of assertion.

Explanation:

• The acid-insoluble pool, also known as the macromolecular fraction, contains large biomolecules that do not dissolve in acid. These include proteins, nucleic acids (DNA and RNA), and polysaccharides.
• Lipids are a diverse group of molecules that are hydrophobic or amphipathic. They are crucial components of cell membranes and play roles in energy storage and signaling.
  • Assertion (A): The acid-insoluble pool contains large biomolecules such as proteins, nucleic acids, and polysaccharides. This statement is correct as these macromolecules are known to be part of the acid-insoluble pool.
  • Reason (R): Lipids, although they do not exceed 800 Da, are classified under the acid-insoluble pool due to their structure and presence in membranes. This statement is also correct. Despite their relatively smaller size, lipids are included in the acid-insoluble pool because they form membrane structures and are not soluble in acid.
  • The reason provides the correct explanation for the assertion because it clarifies why lipids, despite their size, are included in the acid-insoluble pool.

The correct answer is a, e

Concept:

• The mesoderm is one of the three primary germ layers in the early embryo. The other two layers are the ectoderm and the endoderm.
• In some animals, mesoderm forms a continuous layer, while in others it is present as scattered pouches or blocks.
• Animals in which the mesoderm is present as scattered pouches are generally those that have a pseudocoelom or a coelom that is not fully lined by mesoderm-derived tissue.

Explanation:

• Ascaris: This is a genus of parasitic nematode worms, which are pseudocoelomates. In pseudocoelomates, the mesoderm is not a continuous layer but is present in scattered pouches. Hence, Ascaris fits the description.
• Ancylostoma: This is a genus of parasitic hookworms, which are also pseudocoelomates. Like Ascaris, Ancylostoma has a mesoderm present as scattered pouches. Thus, Ancylostoma also fits the description.
• Aptenodytes: This is a genus of birds, specifically penguins. Birds are coelomates with a well-developed and continuous mesoderm.
• Fasciola: This is a genus of parasitic liver flukes, which are acoelomates. Acoelomates have no body cavity, and their mesoderm forms a solid mass of cells. 
• Adamsia: This is a genus of sea anemones, which are coelenterates. Coelenterates have a simple body plan with two germ layers (ectoderm and endoderm) and lack a true mesoderm. 

Thus, based on the presence of the mesoderm as scattered pouches, the correct answer is a, e.