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

Berkeley bodies are found in

  1. Candida utilis

  2. Kluyveromyces lactis

  3. Aspergillus niger

  4. Saccharomyces cerevisiae

  5. Penicillium chrysogenum
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct because Saccharomyces cerevisiae is currently the only yeast cell that is known to have Berkeley bodies present.

Multiple choice

Ringworm disease is caused by

  1. tapeworm

  2. earthworm

  3. fungi

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

Ringworm (tinea) is a fungal infection caused by dermatophytes, which are a type of fungi that grow on skin, hair, and nails. Despite its name suggesting a worm, it has no relation to actual worms like tapeworms or earthworms. Bacteria cause different types of infections altogether.

Multiple choice

Consider the following diseases of plants:

  1. Root knot of sugar-cane.
  2. Root rot of wheat.
  3. Wilt of cotton.
  4. Angular leaf spot of cotton. Which of these diseases is/are caused by fungi?

  1. 1 and 4 only

  2. 2 only

  3. 2 and 3

  4. 1,3 and 4

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Root knot of sugar-cane (Meloidogyne) and wilt of cotton (Verticillium/Fusarium) are caused by nematodes, not fungi. Angular leaf spot of cotton (Xanthomonas) is bacterial. Only root rot of wheat is fungal (Gaeumannomyces/other fungi). Therefore, 1, 3, and 4 are not caused by fungi.

Multiple choice

Which one of the following pairs is not correctly matched?

  1. Tikka disease of ground-nut : Cercospora personata

  2. Blast of rice : Ephellis oryzae

  3. Red rot of sugar-cane : Colletotrichum falcatum

  4. Early blight of potato : Alternaria solani

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Blast of rice is caused by the fungus Magnaporthe oryzae (formerly Pyricularia oryzae), not Ephellis oryzae. The other crop-disease pairings for tikka disease, red rot of sugarcane, and early blight of potato are correctly matched.

Multiple choice

B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein and exist as inactive protoxins, but once an insect ingests the inactive toxin, it is converted into an active form of toxin. This is due to __________.

  1. the acidic pH of the gut, which solubilises the crystals

  2. the neutral pH of the gut, which solubilises the crystals

  3. the alkaline pH of the gut, which solubilises the crystals

  4. the alkaline pH of the respiratory tract, which solubilises the crystals

  5. the acidic pH of the respiratory tract, which solubilises the crystals
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

B. thuringiensis forms protein crystals during a particular phase of its growth. These crystals contain a toxic insecticidal protein and exist as inactive protoxins, but once an insect ingests the inactive toxin, it is converted into an active form of toxin.

Multiple choice

Which of the following features is similar in both monerans and fungi?

  1. Structure of fruiting body

  2. Absorptive heterotrophy

  3. Cellular structure

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

Both monerans (bacteria) and fungi are absorptive heterotrophs - they absorb nutrients from their environment rather than ingesting food. This nutritional mode is the key similarity between these two groups, despite their many other differences.

Multiple choice

The cell wall of fungi is made up of

  1. chitin

  2. cellulose

  3. peptin

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

Fungal cell walls are composed of chitin, a tough polysaccharide also found in insect exoskeletons. This distinguishes fungi from plants (cellulose cell walls) and bacteria (peptidoglycan cell walls). Option C's 'peptin' appears to be a typo for pectin.

Multiple choice

Mushroom is a/an

  1. saprophyte

  2. facultative parasite

  3. autotroph

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

Mushroom is a saprophyte.

Multiple choice

What is the mode of nutrition of Rhizopus, Yeast and Pencillium?

  1. Parasitic

  2. Saprophytic

  3. Symbiotic

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

Rhizopus, yeast, and Penicillium are fungi that obtain nutrition by secreting enzymes onto dead organic matter and absorbing the broken-down products - this is saprophytic nutrition. Parasites feed on living hosts, symbionts have mutual relationships, and autotrophs produce their own food.

Multiple choice

Which of the following is saprophytic in nutrition?

  1. Fungi

  2. Virus

  3. Algae

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

Fungi obtain nutrition by absorbing dissolved organic matter from dead substrates - the saprophytic mode. Viruses are non-living, algae are photosynthetic autotrophs, and cyanobacteria are also photosynthetic - none share the fungal absorptive heterotrophic nutrition.