Nematodes, their life cycle, and the importance of the egg stage

Question 1

phylum occupying most environmental habitats

Answer 1

Phylum Nematoda

Question 2

first animal to have its whole genome sequences

Answer 2

Caenorhabditis elegans

Question 3

notable feature in phylum nematoda

Answer 3

parasitism

Question 4

estimated crop loss

Answer 4

8.8% - 14.6%

Question 5

people infected with STH

Answer 5

~1.45 billion people

Question 6

canonical nematode life cycle

Answer 6

1. embryonation
2. hatching
3. growth and moulting
4. reproduction

Question 7

have only 3 juvenile stages

Answer 7

Xiphinema spp.

Question 8

1st molt occurs inside egg

Answer 8

• Meloidogyne spp.
• Globodera spp.

Question 9

1st and 2nd molt occurs inside egg

Answer 9

Ascaris spp.

Question 10

can be readily sampled from patients and environments

Answer 10

egg stage

Question 11

nematodes that are parthenogenic

Answer 11

• Meloidogyne spp.
• Strongyloides spp.

Question 12

role of egg

Answer 12

1. provides contained environment in which embryonation and occasionaly moulting can occur
2. acts as a protective shield
3. serve as vehicle for larvae to reach site of hatching and infection

Question 13

composition of egg

Answer 13

1. lipid
2. chitin
3. vitelline layers
4. uterine layers (some species)

Question 14

can remain viable for 10 years in the environment

Answer 14

• Trichuris suis
• Ascaris suum

Question 15

hatches in response to caecal but not ileal contents

Answer 15

Trichuris muris