Biology

Microbes and Plant Diseases

1,118 Questions

Microbes and plant diseases examine the role of fungi, bacteria, and viruses in causing infections in plants and humans. Topics cover symbiotic associations like mycorrhiza, fungal structures, and specific agricultural pathogens. Practice these biology questions to master microbiology concepts for upcoming competitive examinations.

Fungal associationsPlant pathogensMicrobial structuresBacterial infections

Microbes and Plant Diseases Questions

Multiple choice plant diseases keeping diseases away biology

Which of the following is not a fungal disease?

  1. Red rot of sugarcane

  2. Wilt of arhar

  3. Brown leaf spot of rice

  4. Potato mosaic
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Potatoes may be infected with many different viruses that can reduce tuber quality and yield. Mosaic virus of potatoes is one such disease that actually has multiple strains. Potato mosaic virus is divided into three categories. Symptoms of the different mosaic virus of potatoes may be similar, so the actual type usually can’t be identified by symptoms alone and is often just referred to as mosaic virus in potatoes. The three types of recognized mosaic virus in potatoes are Latent (Potato virus X), Mild (Potato virus A), Rugose or Common mosaic (Potato virus Y).

So the correct option is 'potato mosaic'.


Multiple choice botany modes of reproduction introduction to flower pre fertilization - plants sexual reproduction in flowering plants the origin of cells and cell division

When a dicot plant is infected by Agrobacterium tumefaciens, the T-DNA in Ti-plasmid induces the plant to produce?

  1. Growth hormones like auxins and cytokinins

  2. Growth inhibitors like absciscic acid

  3. Fatty acids

  4. Leghaemoglobin
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Agrobacterium tumefaciens is the causal agent of crown gall disease (the formation of tumours). It is a rod-shaped, Gram-negative soil bacterium. The plasmid of this bacterium is called Ti-plasmid, it shows T-DNA. This plasmid used to produce growth hormones like auxins and cytokinins.

So, the correct option is ‘Growth hormones like auxins and cytokinins’.

Multiple choice botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

Mycorrhiza is the

  1. Symbiotic association between fungus and roots of seed plants.

  2. Parasitic association between fungus and the roots of seed plants.

  3. Saprophytic association between fungus and roots of seed plants.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Mycorrhiza refers to the symbiotic association of a fungus and roots of vascular plants. During this association, the fungus colonizes on the roots of the host seed plants either intracellularly or extracellulary and is generally mutualistic rather than pathogenic.

Thus, the correct answer is option A.

Multiple choice botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

Mycorrhiza, a relationship between fungi and roots of higher plants is

  1. Parasitic relationship

  2. Saprophytic relationship

  3. Symbiotic relationship

  4. Epiphytic relationship
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Mycorrhiza is a symbiotic association between Fungi and roots of higher plants, which grow in mineral deficient soil. It helps to absorb water and minerals like phosphorous from soil for the benefit of plant and in turn gets nutrition from the plant, as fungi cannot synthesize its own food.

So, the correct answer is option C.

Multiple choice botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

A symbiotic association between fungus and underground part of a plant is

  1. Hyperparasite

  2. Mycorrhiza

  3. Endophyte

  4. Subterranean parasite
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A. Hyperparasite is an organism which lives off another parasite.

B. Mycorrhiza is the symbiotic relationship between vascular plant root and fungi. Its name comes from "myco" means fungi and "rhiza" means roots. Fungi come into direct contact with plant roots and with soil, adding to the plant's ability to gather nutrients and water from the soil through the fungus.
C. Endophyte is a bacterium or fungus which lives inside the plant for at least a part of its life cycle.
D. subterranean parasite is a parasite which lives underground on roots etc 
So, the correct answer is 'Mycorrhiza'.

Multiple choice botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

In what way does a fungus growing around the roots of higher plants benefit them?

  1. It products antimicrobial substances

  2. It produces growth promoting substances

  3. It helps in absorbing water nitrogen and other minerals

  4. All of them
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The associations between roots and fungi are called mycorrhizae. The roots provide essential nutrients for the growth of the fungi. In return, the large mass of fungal hyphae acts as a virtual root system for the plants, increasing the amount of water and nutrients that the plant may obtain from the surrounding soil. So, the correct option is "D" (All of them)
Multiple choice botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

The symbiotic association between fungi and roots of higher plants is referred to as:

  1. lichen

  2. mycorrhiza

  3. biofertiliser

  4. biocontrol agent
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • The symbiotic association between fungi and roots of higher plants is referred to as mycorrhiza.
  • The plant supports the fungus by providing carbohydrates needed for fungal growth, while the fungus helps the plant by increasing its root surface area.
  • So, the correct answer is 'Mycorrhiza'.
Multiple choice botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

Select correct statement w.r.t. mycorrhiza 

  1. Ectomycorrhiza forms hartig net in the intracellular spaces of cortex cells

  2. Endotrophic mycorrhiza are mostly basidiaamycetes members

  3. VAM is a special type of endomycorrhiza and absorbs phosphate

  4. Mycorrhizal or fungal roots have root cap and root hairs
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • The ectomycorrhiza's hyphae does not penetrate the cortex cells and they only colonize in the intercellular spaces between them, and this network of hyphae are called as hartig net. So, the first statement is correct.
  • The endotrophic mycorrhiza are a type of arbascular mycorrhiza.
  • Vesicular arbascular mycorrhiza help the plants to grow well by colonizing their roots and helping them to efficiently absorb the phosphate in the soil.
  • So the correct option is 'VAM is a special type of endomycorrhiza and absorbs phosphate'.

Multiple choice botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

Which one of the following is a useful functional association between fungi and the roots of higher plants?

  1. Lichen

  2. Coralloid root

  3. Biofertilizer

  4. Mycorrhiza
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mycorrhiza is a useful functional association between fungi and the roots of higher plants in which fungi absorb nutrients from the soil as their roots are not such strong and the tree provides food to the fungi. The best example is Orchid mycorrhiza

So the correct option is 'Mycorrhiza'

Multiple choice botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

VAM (Vesicular-arbuscular mycorrhizae) represents

  1. Saprophytic bacteria

  2. Symbiotic fungi

  3. Saprophytic fungi

  4. Parasitic algae
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mycorrhiza biofertilizer is also known as VAM, adheres to plants rhizoids leading to development of hyphae. Hyphae boost development and spreading of white root in to soil leading to significant increase in rhizosphere. These hyphae further penetrate and form arbuscules within the root cortical. VAM fungi form a special symbiotic relationship with roots of plant that can enhance growth and survivability of colonized plants. Mycorrhiza biofertilizer is very useful in organic farming as well as normal commercial farming. So, VAM is a symbiotic fungi and not a parasitic algae, saprophytic bacteria and saprophytic fungi. Thus, the correct answer is option B.