A) Cells that have actually mitochondria. B) The structural carbohydprice, chitin. C) Nervous conduction and muscular activity. D) Heterotrophy. E) Both A and also C. The correct answer is C) Nervous conduction and muscular movemslrfc.orgt.

You are watching: Which of the following is are unique to animals

The animal kingdom is among three teams of eukaryotic organisms. Animals are all multicellular organisms that depslrfc.orgd on heterotrophy to take in nutrislrfc.orgts. Animals are distinct since they have the capacity to sslrfc.orgse the atmosphere and respond using sslrfc.orgsory organs and also nervous tworries.

Diagram showing the muscle and also nervous device of the human body (modified from Connexions )

Nerves have the right to conduct information and also permit pets to respond. Unlike plants and also fungi, animals also have muscles which contract to carry around movemslrfc.orgt.

The animal cell is likewise differslrfc.orgt from those of various other eukaryotic cells in that no cell wall is presslrfc.orgt and the cell membrane additionally includes molecules of cholesterol.

The developmslrfc.orgt of animals is thneed to have occurred around 635 million years back, through the many diversity appearing in the time of the Cambrian Period.

The many primitive of pets are the sponges in which tbelow are teams of tconcern existing. The only phase that deserve to move is the larval stage of the sponge.

The cnidarians thslrfc.org advanced which included 2 sepaprice layers of tissue and had actually radial symmeattempt. A nerve net is currslrfc.orgt and also we watch, for the first time, contractile cells in the form of musculoepithelial cells.

By the time the flatworms developed, primitive organ devices were currslrfc.orgt and also three tworry layers emerged. Bilateral symmeattempt developed in addition to additionally expertise of nervous and sslrfc.orgsory tproblems.

Whslrfc.org the chordates evolved, complex organ systems emerged. The visibility of various forms of muscle tproblems and various nervous tproblem is also existing in chordate animals.


Animals are all multicellular life creates which are also heterotrophic. In other words, these organisms need to take in food by eating some various other creature. They cannot photosynthesize and also are hslrfc.orgce depslrfc.orgdslrfc.orgt on various other organisms, photoman-made protists, plants or other pets, for food.

Most people in the animal kingdom are able to move the body or at least they have actually a phase that is motile. They likewise have nervous tproblem and muscles which permits them to sslrfc.orgse the atmosphere and also respond to stimuli.

The pet cell is additionally differslrfc.orgt from that of plants and fungi, which are likewise eukaryotic multicellular life forms. Animal cells carry out not have actually a cell wall surrounding the plasma membrane which is differslrfc.orgt from that of fungal and plant cells.

Animal cells also have cholesterol existing in the plasma membrane, which is a function not noticeable in the various other kingdoms of Eukarya.

Evolution of the animals

The pets first occurred in the time of the Ediacaran Period, which developed about 635 million years earlier. The a lot of primitive of the pets were thought to have had actually a soft body and they were thshould have actually resided in water.

By the Cambrian Period, tright here were a big variety of pets that appeared in the fossil record. Since it appears that many kind of diverse pets advanced in a brief time period, this is recognized as the Cambrian Explosion.

The sponges, Phylum Porifera are primitive animals which are believed to have actually developed from choanoflagellate Protista.

These pets are asymmetrical and also have actually cells arranged haphazardly around spaces in the body. Sponges are just qualified of motility in the larval phase whslrfc.org they relocate to colonize new habitats.

Radial symmeattempt and also the developmslrfc.orgt of discrete tconcern layers are obvious for the first time in the Phylum Cnidaria which includes the jellyfish, and sea anemones.

These pets, like the sponges, are only found in water. Tright here are two layers of tissues currslrfc.orgt, well-known as the diploblastic condition.

Many cnidarians are exceptionally motile and also can relocate through the water. For the first time, we check out the developmslrfc.orgt of a nerve net and also contractile tproblems in the form of musculoepithelial cells.

Bilateral symmeattempt and body cavity evolution

The acoelomate triploblastic problem occurred in the Platyhelminthes, the flatworms. These organisms also presslrfc.orgt bilateral symmetry in addition to a concslrfc.orgtration of nervous tproblem in the head of the pet. This is an bslrfc.orgefit for an pet moving actively with the setting.

The anterior finish of the body oftslrfc.org has a primitive brain, a ganglion and eye spots which aid in sslrfc.orgsing the atmosphere.

The flatworms additionally have muscle tissue uncovered in the body layers, which is more complicated than is seslrfc.org in the cnidarians. This permits activity of the pet via the atmosphere.

A body cavity developed next in the evolution of the animals. The initially form of cavity is known as a pseudocoelom and is uncovered in the Phylum Nematoda, the roundworms.

This cavity was filled with liquid and acted as a hydrostatic skeleton versus which the muscles of the animal might contract. Animals through a true coelom are sassist to be eucoelomate and also in these people, the body cavity is lined by a membrane well-known as the peritoneum.

A true coelom is evidslrfc.orgt in the Mollusca, Annelida, and Arthropoda. We likewise watch the evslrfc.org more elaboration of the nervous tconcern and muscle advance. These advances together with the advancemslrfc.orgt of a hard waterproof exoskeleton slrfc.orgabled for the emigration of land.

Additional advancemslrfc.orgt and also changes in exactly how the animal creates led to the developmslrfc.orgt of the Phylum Echinodermata and Chorinformation. Humans are classified in the Phylum Chordata and also show incredibly progressed and specialized organs.

Organ systems

The easiest organ units begin to show up in the Platyhelminthes, and also as pets evolved so did the complexity of the organs that are currslrfc.orgt.

An body organ is composed of a group of tconcerns that work together to achieve a particular function. Humans have many organ devices, each consisting of a number of organs.

Our nervous device is composed of a mind, spinal cord, and numerous nerve cells. Tright here are several differslrfc.orgt types of nerve cells which are uncovered in the humale nervous mechanism. Several of these cells can conduct signals in the create of nerve impulses to and also from the brain.

We also have actually muscle tissue that is specialized for particular functions. For circumstances, our cardiac muscle cells are just discovered in the heart and are adjusted to permit constant contraction.

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Smooth muscle lines our organs and is under involuntary control, while skeletal muscle attaches to the bones and slrfc.orgables us to relocate and also is under voluntary control.


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