Biology, 08.06.2021 16:40, saniyaf125

There are three complete tissue layers. b. Flatworms may be either free living or parasitic. c. Flatworms have a sac body plan, with only a mouth and no anus. d. Parasitic flatworms have a well-developed head with eyespots and nerves concentrated into a brain. e. Most planaria are found in marine environments, but some dwell in freshwater and moist terrestrial environments.

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answered: unknown5351

Complete question:

Which of the following statements is NOT correct about the flatworms?

A. There are three complete tissue layers.

B. Flatworms may be either free-living or parasitic.

C. Flatworms have a sac body plan, with only a mouth and no anus.

D. Parasitic flatworms have a well-developed head with eyespots and nerves concentrated into a brain.

E. Most planaria are found in marine environments, but some dwell in freshwater and moist terrestrial environments.

D. Parasitic flatworms have a well-developed head with eyespots and nerves concentrated into a brain.

Explanation:

Flatworms are inferior organisms, meaning that they do not have nerves concentrated in a brain. Their nervous system is, in general, composed of nerve cords forming a net. The arrangement depends on each of the groups. They have one or more pairs of primitive eyes, which function is to find the light. These eyes cup-shaped and are composed of pigmentary cells.

Flatworms have bilateral symmetry. Their body is plane dorsoventrally and can be divided into two specular halves by the sagittal plane. This plane crosses through the body from the anterior extreme to the posterior extreme. The frontal plane divides the body into two different halves, the ventral one with the mouth and the dorsal one.

These organisms only have one opening in their bodies directed to the digestive system, which is the mouth.

Flatworms are aquatic and, most of them are marine animals, although there can be a few groups that inhabit freshwater. Some species might even be terrestrial. Most of them are free-living organisms, but there are also some parasitic forms.

answered: Guest

answer: carbon 14 can only be used to determine the age of the organisms that were once living, and igneous rocks are non living.

explanation:

carbon 14 dating is used to determine the age of the sample by estimating the amount of carbon 14 present in the sample and then comparing it with a reference standard.carbon 14 is a isotope of carbon which is radioactive and unstable. carbon 14 is assimilated by all plants and animals throughout their life from carbon dioxide. however, one the organisms die they stop this assimilation and the carbon 14 content starts to decrease.by knowing how much of carbon 14 is left in an organism after his death, one can estimate the age of the organism. the materials whose age can be estimated by carbon 14 method are the organic compounds. however, some inorganic compounds such as aragonite shell can also be dated.however, if we consider the igneous rocks it is a non living component which never accumulated carbon 14 in it and thus, we cannot use carbon 14 dating method to estimate its age.

answered: Guest

It would be 232.4242

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There are three complete tissue layers. b. Flatworms may be either free living or parasitic. c. Flat...