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1800-102-2727Animals, a very common name, that all of you have heard and seen. Have you ever thought if animals occupy a distinct place in the classification systems proposed by biologists? The answer is yes! Animals are grouped under a separate category called Kingdom Animalia. This forms the fifth kingdom in Whittaker’s Five Kingdom Classification.
Let’s go through some of the general facets of animals.
Kingdom Animalia includes eukaryotic, multicellular heterotrophic organisms which lack a cell wall called Animals.
The bodies of animals show different levels of organisation, i.e., cellular, tissue, organ and organ system level of organisation, to perform diverse functions of the body.
Definite growth patterns have been shown by animals. Embryos or larvae grow into adults having definite size and shape.
Complex and higher invertebrates and vertebrates possess sensory mechanisms to sense changes in their external environment. They also possess neuromotor mechanisms which ensure prompt response to any stimuli.
Most of the animals possess locomotory organs such as limbs, parapodia, etc. for locomotion.
Animals cannot synthesise food on their own. They depend on plants directly or indirectly for satisfying their nutritional requirements. Thus, they show a heterotrophic mode of nutrition.
Most of the animals have a holozoic mode of nutrition. This implies that animals engulf food as a whole and digest within their body, usually extracellularly in a specialised organ system called the digestive system. Few animals also exhibit intracellular digestion (digestion inside cells). Storage of reserve food material occurs in the form of glycogen or fat.
Most of the animals reproduce sexually (involves fusion of gametes from opposite sexes) while a few of them reproduce asexually (single parent produces genetically identical daughter cells). For example, Hydra reproduces asexually by means of budding.
Male and female animals copulate for sexual reproduction. Gametes are formed inside organisms. Gametes of opposite sexes fertilise to form zygotes followed by embryological development.
Fertilisation can be external (outside the female body) or internal (inside the female body) which varies among different animals.
Development can be direct (the embryo develops directly into smaller versions of adult forms) or indirect (the embryo develops into adults through intervening larval stages which are morphologically different from the adults). Some animals develop indirectly by forming larvae.
Based on their characteristic features, animals can be classified into different phyla.
Solution: Cells of animals lack a cell wall while the plant and bacterial cells have it. Animal cells also have fewer vacuoles compared to plant cells. Hence, the given specimen is an animal cell.
Hence, the correct option is b.
Solution: Based on the presence of notochord, animals are classified into two major groups. These are chordates and non-chordates.
Hence, the correct option is a.
Solution: Protists are unicellular eukaryotic organisms. Animals are usually multicellular organisms having eukaryotic cells. Hence, cellularity is the distinguishing feature between prokaryotes and eukaryotes.
Hence, the correct option is c.
Solution:
Features |
Plant cell |
Animal cell |
Cell wall |
Present |
Absent |
Locomotory abilities |
Absent |
Present |
Reserve food material |
Starch |
Glycogen |
Hence, all the features mentioned in the options are differentiating criterias between plant cells and animal cells.
Hence, the correct option is d.
Question1.- Mention three prominent facets of animals.
Answer. Three prominent facets of animals are as follows:
Question2.- Plants exhibit locomotion while animals exhibit movement
Answer. Plants cannot change their position by undergoing displacement, hence, they don’t exhibit locomotion. However, they show a change in position of body parts, thus showing movements. On the other hand, animals exhibit both locomotion (displacement) and movement (change in position of body parts).
Question3.- Mention the types of development undergone by an embryo.
Answer. Development can be of the following types:
Question4.- Define holozoic mode of nutrition.
Answer. The mode of nutrition in which an animal engulfs food as a whole (ingestion), digests which is followed by absorption and assimilation of nutrients and egestion of undigested waste is called the holozoic mode of nutrition.