Question

7 describe the advancements in the specialization of the digestive tract of earthworms in comparison to previously studied animals.
8 discuss the role of the cuticle in the earthworm (lumbricus).
9 discuss the differences between (1) fertilization in dioecious animals such as mammals, (2) self - fertilization in monoecious animals such as tapeworms, and (3) cross - fertilization in hermaphroditic (monoecious) animals such as earthworms.

Explanation:

Question 7:

Earthworms have a more specialized digestive tract with distinct regions like the pharynx for ingestion, gizzard for grinding food, and intestine for digestion and absorption, which is an advancement compared to simpler - gut animals that may lack such differentiation.

Question 8:

The cuticle in earthworms (Lumbricus) serves as a protective layer, preventing desiccation, and also aids in locomotion as it provides a surface for muscle attachment.

Question 9:

In dioecious animals like mammals, fertilization occurs between two different individuals (male and female), with male gametes fertilizing female gametes externally or internally. Self - fertilization in monoecious animals like tapeworms involves the fusion of male and female gametes produced within the same individual. Cross - fertilization in hermaphroditic (monoecious) earthworms involves two individuals exchanging sperm, and then fertilization occurs within each individual's body.

Answer:

Question 7:

Earthworms have a more region - differentiated digestive tract for better ingestion, grinding, digestion, and absorption compared to simpler - gut animals.

Question 8:

The cuticle protects from desiccation and aids in locomotion.

Question 9:

Dioecious mammals have inter - individual fertilization; tapeworms self - fertilize within one individual; earthworms cross - fertilize between two individuals with sperm exchange.