Biology Test 375

The correct answer is 32 Bivalents, 64 centromere, 128 chromatid

Explanation:

• In meiosis, the chromosome number is halved during gametogenesis to result in haploid gametes.

• Metaphase-I of meiosis is the stage where homologous chromosomes (each consisting of two sister chromatids) align at the metaphase plate as bivalents (pairs).

• Each bivalent has two homologous chromosomes, and each chromosome consists of two sister chromatids connected by a centromere.

Given that n = 32 (haploid chromosome number), during metaphase-I:

• There will be 32 bivalents (each consisting of a pair of homologous chromosomes).

• Each bivalent has two centromeres (one per chromosome), hence there will be 64 centromeres.

• Each chromosome has two sister chromatids, and since there are 64 chromosomes in total (2n), there will be 128 chromatids.

The correct answer is All of these

Explanation:

Aestivation refers to the way sepals or petals are arranged in relation to each other in the bud. The four main types of aestivation are valvate, twisted, imbricate, and vexillary (also known as papilionaceous).

A. Valvate: In this type of estivation, the sepals or petals touch each other at the edges without overlapping. This is seen in Calotropis.

B. Twisted: In this type, one margin of each petal or sepal overlaps the next one, and the other margin is overlapped by the previous one. This is observed in China rose, Cotton and Lady's Finger (Okra).

C. Imbricate: In this type, the margins of the sepals or petals overlap each other but not in any particular direction. Cassia and Gulmohar exhibits this type of aestivation.

D. Vexillary: Also known as papilionaceous estivation, it is a specialized type of imbricate estivation where the largest petal (standard) overlaps the two lateral petals (wings), which in turn overlap the two smallest petals (keel). This type is characteristic of the family Fabaceae, such as in Pea, Beans.

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

Explanation:

• Fungi are a diverse group of organisms that include yeasts, molds, and mushrooms. They play crucial roles in nutrient cycling in an ecosystem.

• Fungi are cosmopolitan, meaning they are found in a wide range of environments including air, water, soil, and on plants and animals. They can survive in diverse conditions due to their ability to produce spores.

• Yeasts are unicellular fungi. They are essential in various industrial processes, including baking and brewing, due to their ability to ferment sugars.

• Yeasts, such as Saccharomyces cerevisiae, play a vital role in the fermentation process used in baking and brewing industries.

Therefore, both statements are correct.

The correct answer is parathyroid

Explanation:

• In humans, four parathyroid glands are present on the back side of the thyroid gland, one pair each in the two lobes of the thyroid gland.

• The parathyroid glands secrete a peptide hormone called parathyroid hormone (PTH).

• The secretion of PTH is regulated by the circulating levels of calcium ions.

• Parathyroid hormone (PTH) increases the Ca²⁺ levels in the blood. PTH acts on bones and stimulates the process of bone resorption (dissolution/ demineralisation).

• PTH also stimulates the reabsorption of Ca²⁺ by the renal tubules and increases Ca²⁺ absorption from the digested food. PTH is a hypercalcemic hormone, i.e., it increases the bloodCa²⁺ levels. Along with TCT, it plays a significant role in calcium balance in the body.

Nerves cells are a highly specialized cell which has no power of division because they do not have Centrosome.

The correct answer is 300 and 1200 mOsmolL^-1

Explanation:

• Mammals have the ability to produce concentrated urine.

• The Henle’s loop and vasa recta play a significant role in this. The flow of filtrate in the two limbs of Henle’s loop is in opposite directions and thus forms a counter current.

• The proximity between the Henle’s loop and vasa recta, as well as the counter current in them help in maintaining an increasing osmolarity towards the inner medullary interstitium, i.e., from 300 mOsmolL^–1 in the cortex to about 1200 mOsmolL^–1 in the inner medulla.

• This gradient is mainly caused by NaCl and urea.

The correct answer is A - III, B - II, C - IV, D - I

Explanation:

• A - C₂H₄ (Ethylene):

  • Ethylene is a gaseous plant growth regulator (PGR).

  • It is involved in the ripening of fruits and other plant processes.

• B - N₆-furfurylamino purine (Kinetin):

  • Kinetin is a type of cytokinin, which is a class of plant growth substances (PGR) that promote cell division.

  • It is an adenine derivative.

• C - Abscisic acid:

  • Abscisic acid is a plant hormone that functions in many plant developmental processes and stress responses.

  • It is a derivative of carotenoids.

• D - Gibberellic acid:

  • Gibberellic acid is a type of gibberellin, which is a class of plant hormones that regulate growth and influence various developmental processes.

  • It is classified as a terpene.

The correct answer is more than 1.

RQ of Organic acids (More than 1)

• Organic acids like - Malic acid (Refer below reaction), Tartaric acid, Oxalic acid are rich in O₂ and require less O₂  for their oxidation, so when the organic acids are oxidized in respiration, the value of R.Q. is greater than one. The reaction & RQ is given below :

The correct answer is A - I, B - IV, C - III, D - II

Explanation:

• Complex I: Also known as NADH dehydrogenase, this complex transfers electrons from NADH to ubiquinone (coenzyme Q), initiating the electron transport chain. It is the first enzyme in the mitochondrial respiratory chain.

• Complex II: Known as succinate dehydrogenase, this complex transfers electrons from FADH₂ to ubiquinone. It is the only complex that is part of both the citric acid cycle and the electron transport chain.

• Complex III: Also known as the cytochrome bc₁ complex, it transfers electrons from ubiquinol to cytochrome c. It plays a critical role in creating the proton gradient used for ATP synthesis.

• Complex IV: Known as cytochrome c oxidase, this complex facilitates the transfer of electrons from cytochrome c to oxygen, forming water. It is the final electron acceptor in the chain and is crucial for the reduction of oxygen to water.

• ATP Synthase: Also known as Complex V, although not always counted among the electron transport chain complexes, it uses the proton gradient generated by the ETC to synthesize ATP from ADP and inorganic phosphate.

Explanation:

How are organisms grouped in a taxonomic hierarchy?

• ​The different organisms in a taxonomic hierarchy are classified into different ranks based on the similarities and differences in their morphological characters.

• The organisms that share the least number of common characteristics among them are placed together in higher ranks in the hierarchy.

• Whereas, the organisms that share a greater number of common characteristics are placed together in lower ranks in the hierarchy.

• Let us understand with an example: Domestic dog ( Canis lupus familiaris) and Domestic cat (Felis catus)

• Both are animals and therefore placed in the same Kingdom Animalia.

• Both the animals belong to the same

  • Phylum - Chordata (because both have a notochord at some point of embryonic development.)

  • Class - Mammalia (because both give birth to young ones and have mammary glands.)

  • Order - Carnivora -(because both have teeth that are adapted for flesh-eating.)

• However, the two organisms are placed in different Families because of their differences among them.

• Dogs belong to Family Canidae (live in groups) whereas cats belong to Family Felidae (prefer living solitary).

• Furthermore, all the animals like domestic dogs, wolves, jackals, foxes, etc. are placed together in the same Family Canidae.

• These animals are then categorized into different ranks (Genus and Species) based on the differences and similarities in their characteristics.

  • Domestic dog - Canis lupus familiaris

  • Indian wolf - Canis lupus pallipes

  • Fox - Vulpes vulpes

  • Jackal - Canis aureus

• From the above information, we can conclude that a domestic dog and a wolf share more common characteristics than with a fox or jackal.

• Thus as we go higher the taxonomic hierarchy from Species to Kingdom the number of common characteristics that they share among them decreases.

• Organisms belonging to the lower rank share a greater number of common characteristics among them.

So from the above-given explanation, the correct answer is option 1.