Free Biodiversity and Variety of Life MCQs with Answers

2051. Cysts are not resistant to _ but spores are:

• A. Light
• B. Desiccation
• C. pH
• D. Heat

Explanation: An endospore bacteria can survive a number of harsh conditions such as heat, drying, radiation, and chemicals. Other organisms form spores, but the bacterial spore is generally more heat-resistant and difficult to denature.

2052. In which phase of bacterial growth, does division at an exponential rate occur?

• A. Lag phase
• B. Log phase
• C. Stationary phase
• D. Decline phase

Explanation: Bacterial colonies progress through four phases of growth: the lag phase, the log phase, the stationary phase, and the death phase. The generation time, which varies among bacteria, is controlled by many environmental conditions and by the nature of the bacterial species.

2053. In many bacteria, the cell wall is enclosed within a slime capsule made up of:

• A. Polysaccharides
• B. Cellulose
• C. Amino acids
• D. Proteins

Explanation: The glycocalyx is an outer coating that covers the outside of the bacterial cell wall. The glycocalyx exists in two forms i.e., capsule and slime. The capsule is a condensed layer that is relatively tightly associated with the underlying cell wall and gives sticky or gummy nature to the cell, whereas, slime is a more loosely attached layer that gives slimy or slippery nature to the cell and can be removed from the cell more easily. Generally, the glycocalyx is made of polysaccharides. However, in some cases, protein can also be present.

2054. The DNA of the bacterium is present in a distinct region called:

• A. Nucleolus
• B. Centrosome
• C. Nucleoid
• D. Nucleus

Explanation: Bacterial chromosomes are located in a nucleoid, a distinct cytoplasmic structure, in which double-stranded DNA is coated with histone-like proteins.

2055. The bacteria can cope in unfavorable condition by producing:

• A. Mesosomes
• B. Zygospores
• C. Endospores
• D. Hyphae

Explanation: Numerous strategies exist in bacteria to cope with stressful conditions including the formation of endospores. An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute family. The primary function of most endospores is to ensure the survival of a bacterium through periods of environmental stress.

2056. The cell membrane of a bacterial cell often invaginates to produce membranous structures referred to as:

• A. Centrosomes
• B. Mesosomes
• C. Dictyosomes
• D. Polysomes

Explanation: Mesosomes or chondroids are folded invaginations in the plasma membrane of bacteria.

2057. Apparently which bacteria is more resistant to antibiotics?

• A. Gram-positive bacteria
• B. Gram-negative bacteria
• C. Both Gram-negative and positive bacteria
• D. None of these options are correct

Explanation: Gram-negative bacteria have an outer layer (membrane) that protects them from their environment. These bacteria can use this membrane to selectively keep antibiotic drugs from entering. Germs get rid of antibiotics using pumps in their cell walls to remove antibiotic drugs that enter the cell. Gram-positive bacteria, those species with peptidoglycan outer layers, are easier to kill - their thick peptidoglycan layer absorbs antibiotics and cleaning products easily.

2058. The shape of Cocci bacteria is:

• A. Spherical
• B. Spring
• C. Rod
• D. Screw
• E. Comma

Explanation: Coccus, plural Cocci, in microbiology, a spherical-shaped bacterium.

2059. Vibrio cholera is an example of _ type of bacteria.

• A. Cocci
• B. Bacilli
• C. Spirilla
• D. Commas

Explanation: Bacteria are classified according to their shape, or morphology. Spherical bacteria are known as cocci, rod-shaped bacteria are bacilli, and spiral-shaped bacteria are spirilla, and comma shaped bacteria are known as Vibrio.

2060. A_ is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent.

• A. Cellular anaerobe
• B. Respiratory anaerobe
• C. Obligate anaerobe
• D. Facultative anaerobe

Explanation: Facultative anaerobes are bacteria that can grow in both the presence or absence of oxygen. In addition to oxygen concentration, the oxygen reduction potential of the growth medium influences bacterial growth. The oxygen reduction potential is a relative measure of the oxidizing or reducing capacity. Obligate anaerobes are those that carry out anaerobic respiration only and can not carry out aerobic respiration even in presence of oxygen. Cellular anaerobes and respiratory anaerobes are terms not used to designate any type of organism.