Test: Zoology Mock Test - 2 - NEET MCQ

The counter current mechanism in the kidney is primarily used for maintaining a high osmolarity in the medullary interstitium. This mechanism, involving the loop of Henle and the vasa recta, is crucial for the kidney's ability to produce concentrated urine, conserving water in the body.

Answer: D. Albinism Albinism is an inherited disorder. The main reasons behind this are: - Genetic Mutation: Albinism is caused by a mutation in one of several genes responsible for the production of melanin, the pigment that gives color to our skin, hair, and eyes. This mutation affects the amount and type of melanin produced in the body, resulting in reduced or absent pigmentation. - Autosomal Recessive Inheritance: Most types of albinism are inherited in an autosomal recessive manner, which means that a person must inherit two copies of the mutated gene (one from each parent) to develop the disorder. If both parents carry one copy of the mutated gene, there is a 25% chance that their child will have albinism. - Various Types: There are different types of albinism, such as oculocutaneous albinism, ocular albinism, and Hermansky-Pudlak syndrome. Each type has specific genetic causes and may present with different symptoms. In contrast, the other mentioned disorders are not inherited: - Leprosy: Leprosy is an infectious disease caused by the bacterium Mycobacterium leprae. It is not genetically inherited but rather transmitted through respiratory droplets or prolonged close contact with an infected person. - Goitre: Goitre is an enlargement of the thyroid gland, which can be caused by various factors such as iodine deficiency, thyroid hormone overproduction or underproduction, and inflammation of the thyroid gland. It is not a genetically inherited disorder. - AIDS: AIDS (Acquired Immunodeficiency Syndrome) is caused by the Human Immunodeficiency Virus (HIV), which attacks the immune system. It is not a genetic disorder but rather a viral infection that can be transmitted through blood, sexual contact, and from mother to child during childbirth or breastfeeding.

Immature male germ cells (also called as spermatogonia) produce sperms in the process of spermatogenesis. Spermatogonia proliferate continuously by mitotic divisions around the outer edge of the seminiferous tubules, next to the basal lamina. Some of these cells stop proliferation and differentiate into primary spermatocytes. After they proceed through the first meiotic division, two secondary spermatocytes are produced. The two secondary spermatocytes undergo the second meiotic division to form four haploid spermatids. These spermatids differentiate morphologically into sperm by nuclear condensation, ejection of the cytoplasm and formation of the acrosome and flagellum.

Stanley Miller in 1953, who was then a graduate student of Harold Urey at the University of Chicago, circulated four gases - methane, ammonia, hydrogen and water vapour in an air tight apparatus and passed electrical discharges from electrodes. He passed the mixture through a condenser. He circulated the gases continuously in this way for one week and then analysed the chemical composition of the liquid inside the apparatus. He found a large number of simple organic compounds including some amino acid such as alanine, glycine and aspartic acid. Glutamic acid was not found.

Increased carbon dioxide concentration in the blood shifts the oxygen-hemoglobin dissociation curve to the right, a phenomenon known as the Bohr effect. This shift facilitates the release of oxygen from hemoglobin to the tissues, where it is needed most, demonstrating the body's intricate mechanisms for adapting to varying oxygen demands.

Gorgonia (sea-fan) is an animal belonging to Phylum Coelenterata. All animals lack cell wall.

(II) Because the invaded land does not have its natural predators.

The universality of the genetic code is a fundamental principle in molecular biology, meaning that the same codon codes for the same amino acid across almost all species. This universality supports the theory of a common evolutionary origin for all life forms.

Explanation:

Goitre is an abnormal enlargement of the thyroid gland, which can have several causes. Here is a brief explanation of the causes mentioned in the options:

A: Iodine deficiency

• Iodine is an essential element required for the production of thyroid hormones. When there is an insufficient amount of iodine in the diet, the thyroid gland tries to compensate by enlarging, leading to the development of a goitre.

B: Pituitary adenoma

• A pituitary adenoma is a benign tumor in the pituitary gland. If it produces excessive amounts of thyroid-stimulating hormone (TSH), it can cause the thyroid gland to enlarge and form a goitre.

C: Grave's disease

• Grave's disease is an autoimmune disorder in which the immune system mistakenly attacks the thyroid gland, causing it to produce excessive amounts of thyroid hormones. This can lead to an enlarged thyroid gland and goitre formation.

D: Excessive intake of exogenous thyroxine

• Excessive intake of exogenous thyroxine (e.g., through thyroid hormone replacement therapy) may actually suppress the natural production of thyroid hormones and reduce the size of the gland. In this case, goitre would not be expected to occur as a consequence.

Therefore, the correct answer is option D: excessive intake of exogenous thyroxine.

The correct answer is D: Golden rice.

- Explanation:
- Golden rice is a transgenic crop enriched with beta-carotene, a precursor of vitamin A.
- Vitamin A deficiency is a leading cause of night blindness in developing countries.
- Consuming Golden rice can help address this deficiency, potentially reducing the incidence of night blindness.
- This biofortified crop is a sustainable solution to combat malnutrition and its related health issues in regions where vitamin A deficiency is prevalent.

Ovulation (release of graafian follicle from the ovary) is controlled by FSH and LH.

Explanation of Answer C: Urea is a waste product that is filtered and excreted by the kidneys through the nephrons. The sequence of structures that urea passes through in the nephron is as follows: 1. Proximal tubule:

• Urea filtration begins in the proximal tubule, where it is filtered from the blood along with water, glucose, and other solutes.
• Some urea is reabsorbed back into the blood, while the rest continues to pass through the nephron.

2. Loop of Henle:

• Urea moves from the proximal tubule into the loop of Henle, which plays a crucial role in the concentration of the urine.
• As the filtrate moves through the loop of Henle, water is reabsorbed, and the concentration of urea increases.

3. Distal tubule:

• After passing through the loop of Henle, urea enters the distal tubule, where further reabsorption of water and solutes occurs.
• Regulation of the acid-base balance and electrolyte concentrations in the blood also takes place in the distal tubule.

4. Collecting duct:

• Finally, urea reaches the collecting duct, where additional water reabsorption occurs in response to the hormone vasopressin (or antidiuretic hormone).
• Urea concentration increases in the collecting duct, and the concentrated urine is eventually excreted from the body.

In summary, the correct sequence of structures that urea passes through in the nephron is: Proximal tubule, loop of Henle, distal tubule, and collecting duct (Answer C).

The presence of glucose in urine typically indicates diabetes mellitus. In this condition, high blood sugar levels lead to glucose spilling over into the urine because the kidneys cannot reabsorb all the glucose filtered by the glomeruli.

Keoladeo Ghana National Park, formerly known as the Bharatpur Bird Sanctuary, is a well-known avifauna sanctuary in Bharatpur, Rajasthan, India, that attracts thousands of birds, particularly during the winter season. There are over 230 bird species known to live here.

Explanation of Answer: The correct answer is A: eight. Here is the explanation: - A cockroach has two ovaries, each containing a specific number of ovarioles. - Ovarioles are the functional units of an ovary responsible for producing eggs. - In each ovary of a cockroach, there are eight ovarioles. - Therefore, the total number of ovarioles in a cockroach is 2 (ovaries) x 8 (ovarioles per ovary) = 16 ovarioles. In conclusion, each ovary of a cockroach contains eight ovarioles, making the correct answer option A.

Muscle tissue plays the vital role of providing movement and heat generation to the organs of the body. Muscle cells are specialized for contractility and electrical conductivity.

The Miller-Urey experiment, conducted in 1953, is indeed significant for understanding the origin of life because it showed that amino acids, the building blocks of life, could form under conditions thought to mimic those of early Earth. This supports the hypothesis that life's basic components could have arisen spontaneously on the prebiotic Earth.

The primary function of the loop of Henle in the nephron is the concentration of urine. It achieves this by creating a concentration gradient in the medulla, which facilitates the reabsorption of water from the collecting duct, thus concentrating the urine.

In sexually reproducing organisms, mutation introduces new genetic variations, and recombination shuffles alleles during meiosis, creating new combinations of genes. Together, mutation and recombination are the primary sources of genetic variation, which is essential for evolution.

Erythropoiesis is a process which produces red blood cells . it stimulated by decreases O2 in circulation , which detected by kidney. that's why the correct ans. is D.

Explanation of the answer: Graafian Follicles: - Graafian follicles, also known as ovarian follicles, are structures found in the ovaries of mammals. - They play a crucial role in the reproductive system by nurturing and releasing mature eggs (ovum) for possible fertilization. - Graafian follicles are named after the Dutch anatomist, Regnier de Graaf, who first described them in the 17th century. Why the answer is d. Ovary of mammals: - Graafian follicles are specific to the ovaries of mammals and are not found in the testis, ovary of frogs, or ovary of cockroaches. - In the mammalian reproductive system, the ovaries produce mature eggs that are released from the Graafian follicles during the process of ovulation. - The presence of Graafian follicles is an essential part of the reproductive process in mammals, enabling the release of mature eggs for fertilization. Other options explained: - Testis of mammal: Graafian follicles are not found in the testis as their primary function is related to egg development and release in the ovaries. - Ovary of frog: Frogs are amphibians and have a different reproductive system compared to mammals. They do not have Graafian follicles in their ovaries. - Ovary of cockroach: Cockroaches are insects and have an entirely different reproductive system compared to mammals. They do not possess Graafian follicles in their ovaries.

Assertion : An individual may have births and deaths, but a population has birth rates and death rates.
Reason : Population ecology links ecology to population genetics and evolution.

A neuron (also known as a neurone or nerve cell) is an electrically excitable cell that processes and transmits information through electrical and chemical signals. These signals between neurons occur via synapses, specialized connections with other cells. A typical neuron possesses a cell body (soma), dendrites, and an axon.

Dengue fever - Aedes aegypti MosquitoMalaria -... more Anopheles MosquitoYellow fever - Female MosquitoElephantiasis - Female Mosquito

The uterus is a female reproductive organ located between the bladder and the rectum, in the pelvic area. The main purpose of the uterus is to nourish a foetus prior to birth. In menstruating females, the ovaries release eggs which travel via the fallopian tubes to the uterus.

At high altitudes, adaptations that facilitate oxygen uptake and transport are beneficial. Increased production of 2,3-BPG, increased RBC count, and increased lung surface area all help improve oxygen availability. However, a decreased affinity of hemoglobin for oxygen would be counterproductive, as it would hinder oxygen uptake by hemoglobin in the lungs.

Explanation:

The heart is often referred to as a "double pump" due to its ability to move blood through two separate circulatory pathways. These pathways are:

1. Systemic Circulation:
- In this pathway, oxygen-rich blood from the heart is pumped to the rest of the body.
- Blood delivers oxygen and nutrients to the body's cells.
- Oxygen-poor blood is then returned to the heart.

2. Pulmonary Circulation:
- In this pathway, oxygen-poor blood is pumped from the heart to the lungs.
- In the lungs, blood picks up oxygen and releases carbon dioxide.
- Oxygen-rich blood is then returned to the heart.

This dual-action of the heart, pumping blood through both systemic and pulmonary circulatory pathways, is the reason it is referred to as a "double pump".

Answer: A. Antagonistic muscles Explanation:

• Antagonistic muscles are pairs of muscles that work together to produce movement but have opposite actions. One muscle contracts (shortens) while the other relaxes (lengthens).
• Triceps and biceps are an example of antagonistic muscles because they control the movement of the arm at the elbow joint. The biceps muscle is responsible for flexing (bending) the arm, while the triceps muscle is responsible for extending (straightening) the arm.
• Involuntary muscles are those that cannot be consciously controlled, such as the muscles in the digestive system. This does not apply to triceps and biceps, as they are under voluntary control.
• Smooth muscles are found in internal organs and are not under conscious control, while triceps and biceps are skeletal muscles that are under voluntary control.
• Sphincter muscles are circular muscles that surround and control the opening and closing of a body passage, such as the anus or the pupil of the eye. Triceps and biceps are not sphincter muscles.

Microbes were killed by heating the meat and the sealed vessel formed a closed system wherein the new microbes could not come in contact with the nutrient medium and hence no spoilage of meat.

Viroids are free RNA particles that lack protein coat. They are infectious agents smaller than viruses.