biology experts- please help!!!?

Question

1. Why do plants and animals that live in the water have a simpler reproductive process than the plants and animals that live on land?

2. Why are many kinds of fish very easily produced in fish hatcheries?

3. Why are egg cells in birds relatively few in number and large in size?

4. Describe the migrations made by salmon and eels for purposes of reproduction.

5. Describe the life history and reproduction of the common toad.

6. Why are hens' eggs very satisfactory for the study of embryology?

7. In what bilaterally symmetrical animals is there only one ovary?

8. Is fertilization necessary in the production of eggs?

9. Describe the development of the rabbit embryo from fertilization to birth.

10. Compare the differences in parental care in the case of fish, birds, and mammals.

Answer 1

I have absolutely no idea, but I can make stuff up. Let's see what I can do with these.

1. In water, gametes will not desiccate. There's no real need, then, for hard shells of the gametes as we see in pollen, or mating. Many marine and aquatic species just expel their gametes into the environment and hope for the best.

2. Most of the fishes successful in hatcheries don't care for their young and aren't particularly nest builders or territorial. So, all the fish farm has to do is to put a load of fertilized eggs in a tank, and the fry will hatch out, no problem, and grow without parental involvement. The fish fry know instinctively, how, when, and what to eat. Very handy.

3. Because they can be. Birds have a considerable amount of parental involvement in their eggs -- protection, warming, etc. The eggs are large to increase the likelihood that the growing embryo will have enough, and the right kind of, sustenance to hatch.

4. Salmon, eels, and a few other creatures return to certain freshwater streams or rivers to mate and lay their eggs. These streams or rivers are similar to the ones in which the particular individual was hatched.

5. There was a ropy string of eggs laid in a shallow pond. The eggs hatched into small tadpoles. These tadpoles were fully aquatic, and got oxygen from the water via gills. The tadpoles grew, ate algae (both filamentous, and algae film), and grew more. After a while, the tadpoles grew hind legs! Still they grew. Then one day, bulges showed at the front of the body. A front leg poked through -- through what had been the gill opening in the side of the head. After that, the tadpole had to surface to gulp air, to breathe. The other front leg poked through. The tadpole's tail was absorbed in the body, while the tadpole underwent the final changes in metamorphosis. When the animal was a perfect little toadlet, it swam ashore. The toad lived on land, eating mites, then aphids, then small insects, then, as it grew, whatever insects and other small arthropods it found and fit into its mouth. Toads hunt during the evening and morning -- light enough to see, but without the burning rays of the sun. During the daytime, toads hang out in moist burrows.
Spring came, and the toads instinctively found the nearest suitable puddle. Males found females, and clasped them in "amplexus." The females released ropy eggs into the water, and the males fertilized them as they were extruded.
That pretty much brings us full circle!

6. They grow readily in incubators, can be turned by hand at regular intervals, are large, are readily available, and predictably hatch in about 21 days.

7. Probably some species of snake.

8. Not always. The (hen) eggs you buy at the grocery store are unfertilized.

9. Ovum is fertilized by sperm to form zygote. Zygote divides, forming multicellular blob. Blob becomes hollow ball of cells. Hollow ball of cells partly turns itself inside out, leaving a mouth pore and an anus pore. Further growth and development of the embryo occurs, along with differentiation of the cells to form tissues and organs. Baby rabbit is born.

10. Birds and mammals take care of their few young for a good long while. Most fish just lay eggs and leave. Some fish take care of their eggs -- but stop taking care of the young only a day or two after hatching. Some fish give live birth, but again, most of these don't take care of the young, or, if they do, they stop after a couple of days.

Answer 2

This is ten questions. I'll answer a couple beforeI run out of time: 1. Land animals evolved from sea creatures...and sometimes vice versa.

3. It takes a lot of energy to make a large cell like that. So animals face a choice:lots of cheap ones or a few expensive ones.

8.fertilization is not necessary for the productionof eggs.

Those life history Q's are too long! Gotta go

Answer 3

1. share a common ancestor
2. simple needs
3. greater chance of reproductive success


6. easily aqcuired, abundant

8. no, eggs produced without fertilization

Answer 4

Both are definitely true. This is why the National Institutes of Health (NIH) have recombinant DNA guidelines for all rDNA research.

Answer 5

Wow, you would have saved more time doing your own homework than typing this lot out! Good luck to you if someone else feels happy doing your studies! Get a book, stay awake in class, go to class even!
Seriously, nice try!