Free Biodiversity and Variety of Life MCQs with Answers

2031. In plants, reproduction through the process of cuttings is advantageous as compared to reproduction through seeds because it

• A. Increases the chances of mutation
• B. Facilitates adaptation to environment
• C. Provides variability in the population
• D. Produces identical offspring in short time

Explanation: The correct answer is Option B: facilitates adaptation to environment. Reproduction through cuttings produces offspring that are genetically identical to the parent, which helps them retain the parent's adaptations to the current environment, ensuring survival and stability.Option A is incorrect because cuttings do not increase mutation rates; they maintain genetic consistency. Option C is incorrect because cuttings produce uniform offspring, not genetic variability. Option D, while true about the speed and uniformity of reproduction, doesn't emphasize the environmental adaptation aspect.

2032. The event which does NOT occur in the life cycle of gymnosperms is the formation of:

• A. Pollen tube
• B. Two male gametes
• C. Endosperm nucleus
• D. Multi-nucleated female gametophyte

Explanation: The correct answer is Option B: two male gametes.In gymnosperms, unlike angiosperms, there is no double fertilization event that results in the formation of two male gametes. Instead, gymnosperms typically produce one sperm cell that fertilizes the egg.

2033. In contrast to the female gametophyte of angiosperms, the female gametophyte of gymnosperms bears two or more

• A. Synergids
• B. Archegonia
• C. Polar nuclei
• D. Antipodal cells

Explanation: Female gametophyte of gymnosperms typically contains archegonia, which are flask-shaped structures containing the egg cell. So option B is correct. The female gametophyte of angiosperm not gymnosperms typically consists of seven cells with eight nuclei: one egg cell, two synergid cells, three antipodal cells, and one central cell with two polar nuclei. So option A, C and D are incorrect.

2034. Select a method which causes the oxidation of chemical constituent of a bacterial cell:

• A. Steam
• B. Dry heat
• C. Filtration
• D. Radiation

Explanation: Dry heat helps kill the organisms using the destructive oxidation method. This helps destroy large contaminating bio-molecules such as proteins. The essential cell constituents are destroyed and the organism dies. The temperature is maintained for almost an hour to kill the most difficult of the resistant spores.

2035. All of the following are examples of substances found in bacteria or archaea except:

• A. Peptidoglycans
• B. Flagellin
• C. Bacteriorhodopsin
• D. Chitin
• E. Phycobilins

Explanation: Chitin is a polysaccharide found in the exoskeleton of arthropods and in the cell walls of fungi. Flagellin is the protein of bacterial flagella. Bacteriorhodopsin is a photosynthetic pigment found in extreme halophiles. Phycobilins are photosynthetic pigments found in cyanobacteria (as well as in red algae).

2036. Which of the following bacteria are without a cell wall?

• A. Mycoplasma
• B. Gram positive bacteria
• C. Gram negative bacteria
• D. Archaeo bacteria

Explanation: Mycoplasma is indeed a bacterium that is known for lacking a cell wall. Unlike most bacteria, Mycoplasma species do not have a rigid cell wall composed of peptidoglycan. Instead, they have a unique cell membrane that provides shape and protection. This membrane contains sterols, which help maintain structural integrity. The absence of a cell wall makes Mycoplasma cells more flexible and pleomorphic (having various shapes).

2037. Gram-negative bacteria are stained pink by the use of:

• A. Crystal violet
• B. Gram's iodine
• C. Feulgen stain
• D. Safranin

Explanation: Option D is correct as gram-negative bacteria are not easily stained by primary dye (crystal violet) so a secondary dye (safranin or fuchsine) is required to dye them a pink or red color.

2038. The first simplest oxygen producing organism:

• A. Methanogens
• B. Cyanobacteria
• C. Euglena
• D. Spirogyra

Explanation: There is suggestive evidence that photosynthetic organisms were present approximately 3.2 to 3.5 billion years ago, in the form of stromatolites, layered structures similar to forms that are produced by some modern cyanobacteria.

2039. Bacterial pilli help in:

• A. Locomotion
• B. Conjugation
• C. Phagocytosis
• D. Pinocytosis
• E. Exocytosis

Explanation: Conjugative pili allow for the transfer of DNA between bacteria, in the process of bacterial conjugation. They are sometimes called "sex pili", in analogy to sexual reproduction, because they allow for the exchange of genes via the formation of "mating pairs". Locomotion is performed by flagella, phagocytosis, pinocytosis, and exocytosis by microtubules.

2040. Which of the following organelles are present in all the bacteria?

• A. Mesosome
• B. Golgi bodies
• C. Mitochondria
• D. Chloroplast

Explanation: Bacteria are prokaryotes. They are made up of single cells. They do not have well-defined nuclei, instead, they possess nucleoids as genetic material. They also lack membrane-bound cell organelles like mitochondria, Golgi bodies, chloroplast, etc. However, they do contain ribosomes and mesosomes in the cytoplasm. Thus, the correct answer is 'Mesosome.'