IIT JAM Biotechnology Past Year Papers - 2018 - Biotechnology Engineering (BT) MCQ

The correct answer is Option A: Toxoplasma gondii.

Here's an explanation of each option:
A: Toxoplasma gondii
- Toxoplasma gondii is a protozoan parasite that belongs to the phylum Apicomplexa.
- Apicomplexa is a group of parasitic single-celled organisms, many of which are medically significant.
- Toxoplasma gondii is the causative agent of Toxoplasmosis, a disease that can cause flu-like symptoms or more severe neurological issues, particularly in immunocompromised individuals and unborn children.

B: Leishmania donovani
- Leishmania donovani is a protozoan parasite that belongs to the phylum Kinetoplastida, not Apicomplexa.
- This parasite is responsible for a disease called visceral leishmaniasis, which affects internal organs such as the spleen, liver, and bone marrow.

C: Entamoeba histolytica
- Entamoeba histolytica is an amoebic parasite that belongs to the phylum Amoebozoa, not Apicomplexa.
- This parasite causes amebic dysentery and liver abscesses in humans.

D: Trichomonas vaginalis
- Trichomonas vaginalis is a flagellated protozoan that belongs to the phylum Parabasalia, not Apicomplexa.
- This parasite is responsible for a sexually transmitted infection called trichomoniasis, which can cause itching, burning, and discharge in women and irritation and discharge in men.

The correct answer is Option (C).

Here's an explanation for each statement:

A: Their cells are of definite shape.
- Incorrect. Mycoplasma has a unique characteristic in that it does not have a cell wall, which gives them a pleomorphic nature, meaning they can change their shape.

B: They are resistant to lysis by osmotic shock.
- Incorrect. Due to the absence of a cell wall, Mycoplasma is actually more susceptible to osmotic shock than other bacteria. The presence of sterols in their plasma membrane provides some resistance to osmotic lysis, but they are not completely resistant.

C: Their growth is not inhibited by penicillin.
- Correct. Penicillin and other beta-lactam antibiotics target bacterial cell wall synthesis. Since Mycoplasma lacks a cell wall, it is naturally resistant to these antibiotics.

D: They are nonpathogenic to human.
- Incorrect. Some Mycoplasma species, such as Mycoplasma pneumoniae, can cause respiratory infections in humans. Other species, like Mycoplasma genitalium, can cause urogenital infections.

Correct answer: C: Endoplasmic reticulum

Endoplasmic reticulum (ER) is an organelle enclosed by a single membrane.

Here is an explanation for each option:

A: Ribosome
- Ribosomes are not enclosed by any membrane.
- They are responsible for protein synthesis.
- Ribosomes are found either freely floating in the cytoplasm or attached to the endoplasmic reticulum.

B: Mitochondria
- Mitochondria are enclosed by two membranes – an outer membrane and an inner membrane.
- They are known as the "powerhouse of the cell" as they produce adenosine triphosphate (ATP) through cellular respiration.

C: Endoplasmic reticulum
- The endoplasmic reticulum is a network of membranous tubules and flattened sacs.
- It is enclosed by a single membrane called the endoplasmic reticulum membrane.
- The ER is classified into two types: smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER).
- The RER is involved in protein synthesis and has ribosomes attached to its surface, while the SER is involved in lipid synthesis and detoxification.

D: Centrosome
- The centrosome is not enclosed by any membrane.
- It is an organelle composed of two centrioles, which play a crucial role in cell division.
- The centrosome helps in the organization of microtubules and provides structure to the cell.

Correct answer is Option (D): always upright.

Explanation:
A pyramid of energy represents the flow of energy through different trophic levels in an ecosystem. In a forest ecosystem, the pyramid of energy is always upright. This is because:

- At each trophic level, only a small fraction of energy is transferred to the next level, while the rest is lost as heat energy due to respiration and other metabolic activities. This results in a progressive decrease in energy as we move up the trophic levels.

- Producers, such as plants and algae, form the base of the pyramid and have the highest amount of energy due to their ability to convert solar energy into chemical energy through the process of photosynthesis.

- Primary consumers, such as herbivores, feed on producers and have a lower amount of energy compared to the producers.
- Secondary consumers, such as carnivores, feed on primary consumers and have even less energy available to them.
- Tertiary consumers, which are top predators, have the least amount of energy available to them as they feed on secondary consumers.

In summary, the pyramid of energy in a forest ecosystem is always upright because energy decreases as we move up the trophic levels, with producers having the highest amount of energy and top predators having the least amount of energy.

Correct answer is  option (B).
Feedback Regulation of Enzyme

• End product binding: The end product binds to the allosteric site of the enzyme.


• Regulation mechanism: This binding causes a conformational change in the enzyme, affecting its activity.


• Allosteric site: A site on an enzyme, separate from the active site, where a molecule can bind and influence the enzyme's activity.


• Active site: The region on the enzyme where the substrate binds and the reaction occurs.


• Enzyme-substrate complex: A temporary complex formed when the enzyme binds to its substrate.


• Substrate: The reactant on which an enzyme acts.


• Feedback inhibition: A mechanism where the end product of a metabolic pathway inhibits an earlier enzyme in the pathway, preventing the overproduction of the end product.


 

The word VIRUS contains 5 letters

so we have to make 3 letter words without repetetion

= ⁵C₁ x ⁴C₁ x ³C₁ 

= 5 x 4 x3 = 60

Correct Answer :- a

Explanation : a) Proline is the only cyclic amino acid. It is nonpolar and shares many properties with the aliphatic group. Proline is one of the ambivalent amino acids, meaning that it can be inside or outside of a protein molecule.

b) Oxytocin (Oxt) is a peptide hormone and neuropeptide. It is normally produced in the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, reproduction, and the during the process of reproduction as "the love hormone" (oxytocin) is secreted during all these processes .

c) Aspartame is an artificial non-saccharide sweetener 200 times sweeter than sucrose, and is commonly used as a sugar substitute in foods and beverages.

d) The β-lactam ring is part of the core structure of several antibiotic families, the principal ones being the penicillins, cephalosporins, carbapenems, and monobactams, which are, therefore, also called β-lactam antibiotics.