Question

ascaris cross section
the thick outer cuticle and underlying epidermis should be easily distinguishable on your slide. beneath these layers are the longitudinal muscles described earlier. embedded within this layer of muscles are the two lateral lines and the dorsal and ventral nerve cords. the nerve cords are depicted in figure 13.6 at the twelve oclock and six oclock positions, and the lateral lines are located at the three oclock and nine oclock positions. a cross - section of the thin, somewhat flattened intestine should be apparent in the pseudocoelom, with the rest of the body cavity occupied by reproductive organs.
differentiating the testis and the vas deferens (on males) or the ovaries, oviducts, and uteri (on females) is generally a matter of distinguishing between the different diameters of these structures. testes and ovaries are always the smallest tubules in the body. the paired uteri are the most easily recognized because of their larger diameters and the fact that they are usually packed with eggs.
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1.1 list two external differences between male and female nematodes.
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2.
1.2 is the intestine surrounded by an outer layer of muscle? (hint: think of the type of body cavity this animal possesses.)
1.3 why do you suppose the digestive system of nematodes is rather unspecialized?
1.4 do nematodes fit the pattern typical of parasites, in that a large portion of their body cavity is devoted to reproductive structures?

Explanation:

1.1: Based on the cross - section images and description, male nematodes have testes and vas deferens visible in the body cavity, while females have ovaries, oviducts, and uteri. Another external difference could be related to body size or shape in some nematode species (though not clearly shown in the cross - section but common in general).
1.2: Nematodes have a pseudocoelom. The intestine is not surrounded by a complete outer layer of muscle as in more complex animals with a coelom. The body cavity (pseudocoelom) provides some space and the muscles are arranged in a different way.
1.3: Nematodes are often parasites. Their diet is relatively simple, usually consisting of nutrients from the host's environment. So, they don't need a highly specialized digestive system to break down a wide variety of complex substances.
1.4: Yes, as seen from the cross - section, a large portion of the body cavity in both male and female nematodes is occupied by reproductive organs (testes, vas deferens in males; ovaries, oviducts, uteri in females), which is typical of parasites that need to reproduce in large numbers to ensure survival and spread.

Answer:

1.1: Males have testes and vas deferens, females have ovaries, oviducts and uteri; Some species may have size/shape differences.
1.2: No, due to the presence of pseudocoelom and muscle arrangement.
1.3: Because they are parasites with a simple diet.
1.4: Yes, a large part of the body cavity is for reproductive structures.