Concept explainers
Test your Understanding
Know and Comprehend
A radially symmetrical animal such as Hydra is likely to have (a) a forebrain (b) a nerve net (c) cerebral ganglia (d) a ventral nerve cord (e) cerebral ganglia and a nerve net
Introduction: Hydra is a freshwater organism of the phylum Cnidaria. They have very high regenerative ability. They are radially symmetrical invertebrates and have tentacles to capture their food.
Answer to Problem 1TYU
Correct answer: Radially symmetrical organisms such as Hydra have simple nervous systems like the nerve net. Hence, the correct answer is option (b).
Explanation of Solution
Reason for the correct answer:
Radial symmetry is generally present in simpler organisms such as Hydra. Organisms belonging to simpler classes in the animal kingdom have less complexed nervous systems. They usually have interconnected networks of neurons, and no central control system is present in such simpler neural systems. Such connection of neurons forms the nerve net.
Option (b) is given as “a nerve net”.
Radially symmetrical organisms such as Hydra have simpler body organization and simpler nervous systems such as the nerve nets. Hence, the correct answer is option (b).
Reasons for incorrect answers:
Option (a) is given as “a forebrain”.
A forebrain is a part of a complex nervous system that is found in higher organisms with a complex body organization. The forebrain is not found in simpler organisms such as Hydra. Hence, option (a) is incorrect.
Option (c) is given as “cerebral ganglia”.
Radially symmetrical organisms have simple nervous systems that do not have any control center. Cerebral ganglia act as a control center in the nervous systems. Hence, option (c) is incorrect.
Option (d) is given as “a ventral nerve cord”.
Ventral and dorsal sides can be defined only in organisms with bilateral symmetry. In organisms with simple body organization, there is no nerve cord present. Thus, radially symmetrical organisms cannot have a ventral nerve cord. Hence, option (d) is incorrect.
Option (e) is given as “cerebral ganglia and a nerve net”.
Simpler organisms do not have cerebral ganglia in their nervous systems. Hence, option (e) is incorrect.
Hence, options (a), (c), (d), and (e) are incorrect.
Organisms with radial symmetry in their body organization, such as Hydra, have a nervous system consisting only of nerve nets.
Want to see more full solutions like this?
Chapter 42 Solutions
Mindtap Biology, 1 Term (6 Months) Printed Access Card For Solomon/martin/martin/berg's Biology, 11th
- Test Your Understanding 2.Which of the following is/are found in tunicates? (a) dorsal, tubular nerve cord (b) tube feet (c) anal gill slits (d) two pairs of appendages (e) vertebral columnarrow_forwardTest Your Understanding 4.Which of the following characteristics is/are associated with amphibians? (a) amnion (b) placoid scales (c) heart with two complete ventricles (d) swim bladder (e) metamorphosisarrow_forwardTest Your Understanding 12 VISUALIZE Label the diagram.arrow_forward
- Test Your Understanding 7.Which of the following is true of mammals? (a) they evolved from saurischian dinosaurs (b) they are exotherms (c) they have hair and three middle ear bones (d) mammalian embryos do not have an amnion (e) they all bear their young alive (do not lay eggs).arrow_forwardTest Your Understanding 3.A shark is characterized by (a) amnion (b) bony skeleton (c) water vascular system (d) placoid scales (e) endothermy and amnionarrow_forwardTest Your Understanding 8. VISUALIZE Label the diagram of the human brain.arrow_forward
- Test Your Understanding 6.Which of the following is not characteristic of birds? (a) hollow bones (b) amnion (c) ectothermy (d) high metabolic rate (e) reptilian-like scales on legsarrow_forwardTest Your Understanding 1.Which of the following is not a shared derived character of echinoderms? (a) water vascular system (b) notochord (c) tube feet (d) pentaradial symmetry in adult (e) endoskeleton of calcium carbonate plates and spinesarrow_forwardThe magnitude of receptor potential in the stretch receptor of a crayfish: a) depends on how much the muscle is stretched b) would decrease as the muscle is stretched c) depends on the amount of neurotransmitter released d) is the same for all types of stimuli e) depends on the strength of in incoming action potentialarrow_forward
- Match the following:(a) Operculum (i) Ctenophora(b) Parapodia (ii) Mollusca(c) Scales (iii) Porifera(d) Comb plates (iv) Reptilia(e) Radula (v) Annelida(f ) Hairs (vi) Cyclostomata and Chondrichthyes(g) Choanocytes (vii) Mammalia(h) Gill slits (viii) Osteichthyesarrow_forwardWhy is it important to study the structure and functions of animal systems?arrow_forwardProvide two concepts for each about the general characteristics of invertebrates (as a whole) as to (a) body plan, (b) niche, (c) locomotion, (d) reproduction, and (e) evolution. General characteristics of invertebrates Body Plan 1. 2. Niche 1. 2. Locomotion 1. 2. Reproduction 1. 2. Evolution 1. 2.arrow_forward
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage LearningBiology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning