BIO 103 Test Your Knowledge Chapter 19

Fossils suggest that the first major trait distinguishing hominins from other primates was

erect posture

The earliest members of the genus Homo

had a larger brain compared to other hominins

A lamprey, a shark, a lizard, and a rabbit share all the following characteristics EXCEPT

hinged jaws

Which of these is not a member of the anthropoids?

tarsier

Compare the adaptations of amphibians and reptiles for terrestrial life

Amphibians have four limbs adapted for locomotion on land, a skeletal structure that supports the body in a nonbuoyant medium, and lungs. However, most amphibians are tied to water because they obtain some of their oxygen through thin, moist skin and they require water for fertilization and development. Reptiles are completely adapted to life on land. They have amniotic eggs that contain food and water for the developing embryo and a shell to protect it from dehydration. Reptiles are covered by waterproof scales that enable them to resist dehydration.

Which of the following correctly lists possible ancestors of humans for the oldest to the most recent?

Australopithecus, Homo habilis, Homo erectus

Birds and mammals are both endothermic, and both have four-chambered hearts. Most reptiles are ectothermic and have three-chambered hearts. Why don't biologists group birds with mammals? Why do most biologists now consider birds to be reptiles?

Fossil evidence supports the evolution of birds from a small, bipedal, feathered dinosaur, which was probably endothermic. The last common ancestor that birds and mammals shared was the ancestral amniote. The four-chambered hearts of birds and mammals must have evolved independently.

Studies of DNA support which of the following?

Homo sapiens originated in Africa

One of the misconceptions about human evolution is expressed in the question "If chimpanzees were our ancestors, then why do chimpanzees still exist?"

In the phylogenetic tree of primates, the last common ancestor of chimpanzees and humans lived more than 6 million years ago. The lineages that led to chimpanzees and humans have been evolving separately since that time.

Explain some of the reasons why the human species has been able to expand in number and distribution to a greater extent than most other animals

Our intelligence and culter-accumulated and transmitted knowledge, beliefs, arts, and products-have enabled us to overcome our physical limitations and alter the environment to fit our needs and desires.

What adaptations inherited from our primate ancestors enable humans to make and use tools?

Several primate characteristics make it easy for us to make and use tools: mobile digits, opposable fingers and thumb, and great sensitivity of touch. Primates also have forward-facing eyes, which enhances depth perception and eye-hand coordination and a relatively large brain.

Why were the Tiktaalik fossils an exciting discovery for scientists studying tetrapod evolution?

They have roughly equal combination of fishlike and tetrapod-like characteristics.

Summarize the hypotheses that explain variation in human skin color as adaptations to variation in UV radiation

UV radiation is most intense in tropical regions and decreases farther north. Skin pigmentation is darkest in people indigenous to tropical regions and much lighter in northern latitudes. Scientists hypothesize that depigmentation was an adaptation to permit sufficient exposure to UV radiation, which catalyzes the production of vitamin D, a vitamin that permits the calcium absorption needed for both maternal and fetal bones. Dark pigmentation is hypothesized to protect against degradation of folate, a vitamin essential to normal embryonic development.