Question

Which of the following is true or false

1) A complex life cycle (where a larva/juvenile undergoes complete metamorphosis to form a highly mobile adult with a completely different morphology and ecology from the larva/juvenile) is associated with extraordinary diversification in some groups of insects.

2) In contrast to the jawless Ostracoderms, the earliest jawed fishes such as the Placoderms were soft-bodied, sleek and unencumbered by heavy outer armor, and fast hunter-predators.

3) Mammals—small, nocturnal, endothermic, with hair (modified scales) for insulation, lactation, 3 inner ear bones, and a strong single dentary bone for biting—arose from the Therapsid reptiles in the early Mesozoic, but lived in the shadow of the great Diapsid reptile radiation until the end of the Mesozoic period.

4) A definitive characteristic of the “Anthropoids” (monkeys + apes + humans) is that they have an opposable thumb, but humans differ from apes in that humans have a non-opposable toe.

5) The fact that both birds and mammals are endothermic and have complex social systems (including extensive parental care of the young), have a four-chambered heart, and have a high metabolic rate and activity level suggests that these two groups are monophyletic, i.e., that they descended from a single reptilian ancestor.

Answer 1

The answers regarding which sentence is true and which sentence is false are as follows-

1) A complex life cycle (where a larva/juvenile undergoes complete metamorphosis to form a highly mobile adult with a completely different morphology and ecology from the larva/juvenile) is associated with extraordinary diversification in some groups of insects.- TRUE

2) In contrast to the jawless Ostracoderms, the earliest jawed fishes such as the Placoderms were soft-bodied, sleek, and unencumbered by heavy outer armor and fast hunter-predators. FALSE

Placoderms had an armored skin that is unique to them and very important in the fossil study.

3) Mammals—small, nocturnal, endothermic, with hair (modified scales) for insulation, lactation, 3 inner ear bones, and a strong single dentary bone for biting—arose from the Therapsid reptiles in the early Mesozoic, but lived in the shadow of the great Diapsid reptile radiation until the end of the Mesozoic period.- FALSE

Therapsids gave rise to mammals. Diapsid reptiles gave rise to lizards.

4) A definitive characteristic of the “Anthropoids” (monkeys + apes + humans) is that they have an opposable thumb, but humans differ from apes in that humans have a non-opposable toe. -TRUE

The hallux which is abducted in humans is responsible for the non-opposable toe. In the course of evolution, humans did not need to grasp onto trees and branches with their opposable toe anymore, thus the modification.

5) The fact that both birds and mammals are endothermic and have complex social systems (including extensive parental care of the young), have a four-chambered heart, and have a high metabolic rate and activity level suggests that these two groups are monophyletic, i.e., that they descended from a single reptilian ancestor.- TRUE

Birds and mammals are monophyletic which mean that they have a common ancestor.