CBSE Questions for Class 11 Medical Biology Biological Classification Quiz 2 - MCQExams.com

A) Correct option C

B) Explanation for the correct option:

Methanogens can be found in the intestines of ruminants such as cows and buffaloes, and they generate methane from their dung. These bacteria have the ability to produce methane, marshland gas, or biogas. Thus, they are found abundantly in cattle yards. 

The term Obligate anaerobes represent such microorganisms which can survive only in the absence of oxygen, i.e. presence of oxygen in their surrounding environment acts as a poison for them. Methane bacteria also called as methanogens are methane-producing bacteria which are obligate anaerobes as their metabolic processes do not require oxygen. Spirogyra are the green algae which produces oxygen. Pisum Sativum is commonly known as Green pea, which is a vegetable. Onion is also a vegetable.

The correct answer is D. 

• The structure of a fungal cell wall is unique to fungi and can protect the cell from osmotic pressure and environmental stresses. 
• The cell wall is made up of chitin (polysaccharide).
• Chitin is constituted by N-acetyl-glucosamine units linked by β-(1 → 4) glycosidic bonds and is after cellulose the second most abundant natural polymer.
  

The term Protists include single cellular microorganisms. These unicellular microorganisms have a highly organized cellular structure. They are eukaryotes means their cell has a nucleus and membrane-bound organelles. They can be either autotroph i.e. can manufacture their food through photosynthesis, or they can also be heterotroph i.e. dependent on other organisms for their survival.

The correct answer is D. 

• Oospores are produced when male gametes (reproductive nuclei) enter a large spherical cell (oogonium) and fertilize the eggs within. The oogonia is usually penetrated by one or more hyphae (antheridia) that give rise to the male nuclei. 

• Zygospores do not occur inside any kind of enclosing structure but are produced by the direct fusion of two hyphal protrusions (suspensors) from neighbouring filaments. Usually, zygospores are recognized as large, nearly spherical, often dark brown or black, rough-walled spores with two connecting hyphae, representing the two mating gametangia. 

• Ascospores are produced within spherical to cylindrical cells called asci, most often in groups of four or eight. Usually, the asci are produced within some kind of enclosing structure and thus, are not found exposed on the hyphae.

• Basidiospores are always produced externally on a structure, called as a basidium. Basidia come in a variety of forms, but those commonly encountered on moulds will be club-shaped and bear four or eight spores on sharp projections at the apex. 

A)      Correct option  (D)
B)      Explanation of the correct option

Isogamy is sexual reproduction by the fusion of similar gametes. Here similar implies similar shape and size of the male and female gametes. Mucor commonly known as a mould is an example of isogamy. Hence correct answer is option A.