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Question
Which of the following has the least number of body segments?
Which of the following has the least number of body segments?
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Solution
The correct option is D Flatworm
- Lobster: The 14 segments that are fused together to make up the cephalothorax are called somites and each somite bears a pair of appendages that are located on different areas of the lobster, usually on either side of the body or on the underside of the body.
- Grasshopper: Insects have three major body regions: head, thorax, and abdomen (see Insect Body Regions, right). The head is made of 5-7 fused segments and bears the eyes, antennae, and mouthparts. The thorax consists of three segments called the pro-, meso-, and metathorax. Appendages used for movement are attached to the thorax. Each of the segments of the thorax bears one pair of legs and if wings are present they are found on the meso- and metathorax only. The top of the prothorax is called the pronotum. An insect's abdomen consists of 11 or fewer segments that generally do not bear any appendages, except for segments near the rear which may have appendages associated with reproduction.
- The earthworm is made of about 100-150 segments. The segmented body parts provide important structural functions. Segmentation can help the earthworm move. Each segment or section has muscles and bristles called setae.
- Flatworms have bodies made of three layers, outer ectoderm, inner endoderm, and in between the mesoderm. There is a definite head and the body usually tapers towards the rear. The characteristic flattening of the bodies gives the group its common name. Unlike in the case of annelid worms (e.g., the earthworm), there is no division of the body into numerous segments. Nor does the middle layer divide to form an internal cavity – the coelom (annelid worms and all higher animals,
So, the correct answer is 'Flatworm'.
- Lobster: The 14 segments that are fused together to make up the cephalothorax are called somites and each somite bears a pair of appendages that are located on different areas of the lobster, usually on either side of the body or on the underside of the body.
- Grasshopper: Insects have three major body regions: head, thorax, and abdomen (see Insect Body Regions, right). The head is made of 5-7 fused segments and bears the eyes, antennae, and mouthparts. The thorax consists of three segments called the pro-, meso-, and metathorax. Appendages used for movement are attached to the thorax. Each of the segments of the thorax bears one pair of legs and if wings are present they are found on the meso- and metathorax only. The top of the prothorax is called the pronotum. An insect's abdomen consists of 11 or fewer segments that generally do not bear any appendages, except for segments near the rear which may have appendages associated with reproduction.
- The earthworm is made of about 100-150 segments. The segmented body parts provide important structural functions. Segmentation can help the earthworm move. Each segment or section has muscles and bristles called setae.
- Flatworms have bodies made of three layers, outer ectoderm, inner endoderm, and in between the mesoderm. There is a definite head and the body usually tapers towards the rear. The characteristic flattening of the bodies gives the group its common name. Unlike in the case of annelid worms (e.g., the earthworm), there is no division of the body into numerous segments. Nor does the middle layer divide to form an internal cavity – the coelom (annelid worms and all higher animals,
So, the correct answer is 'Flatworm'.
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