Chordates, Vertebrates, and Human Evolution: Key Concepts and Traits

What four traits define chordates?

Notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail.

What are the two groups of invertebrate chordates?

Tunicates (Urochordata) and Lancelets (Cephalochordata).

Which invertebrate chordate shows chordate traits only in its larval stage?

Tunicates.

Which invertebrate chordate retains chordate characteristics throughout life?

Lancelets (amphioxus).

What distinguishes vertebrate chordates from invertebrate chordates?

Presence of a vertebral column (backbone) and cranium (skull).

What was the function of the first vertebrate head (cranium)?

Protects the brain and houses sensory organs.

Why were jaws a major evolutionary milestone?

Allowed biting and new feeding strategies.

What did fins provide early vertebrates?

Stability and maneuverability in water.

What structure allowed vertebrates to breathe air?

Lungs (or lung-like structures).

What is the evolutionary significance of limbs with digits?

Enabled movement on land.

What is the advantage of the amniotic egg?

Allows reproduction away from water.

Which two traits define mammals?

Hair and mammary glands (milk).

Why are fish highly successful in water?

Fins, gills, streamlined bodies, lateral line system, swim bladder.

Name two challenges animals faced moving to land.

Avoiding desiccation; supporting body weight against gravity.

How did the amniotic egg help vertebrates colonize land?

Prevents embryo from drying out and provides nourishment.

Name one fossil that shows transition between fish and tetrapods.

Tiktaalik.

What type of evidence supports vertebrate evolution from water to land?

Fossils, comparative anatomy, embryology, DNA.

What does oviparous mean?

Lays eggs.

What does ovoviviparous mean?

Eggs develop inside the mother; young hatch internally or right after.

What does viviparous mean?

Live birth.

What are hagfish known for?

Producing slime and lacking true vertebrae.

What is unique about lampreys?

Jawless vertebrates; often parasitic.

What group includes sharks and rays?

Cartilaginous fish (Chondrichthyes).

Which fish group is closest to tetrapods?

Lobe-finned fish (lungfish and coelacanth).

What is a defining feature of amphibians?

Require water for reproduction.

What allows reptiles to fully live on land?

Amniotic egg and waterproof skin.

What two characteristics define mammals?

Hair and milk production.

What evidence supports human evolution?

Fossils, DNA, tools, anatomy.

What model states that humans originated in Africa and spread outward?

Out-of-Africa model.

What determines variation in human skin color?

Adaptation to UV radiation (vitamin D vs folate protection).

What is biodiversity?

Variety of genes, species, and ecosystems.

What is the biggest cause of biodiversity loss?

Habitat destruction.

Name three ways humans are changing Earth.

Climate change, habitat loss, pollution.

What is conservation biology?

The study and protection of biodiversity.

Are we doomed? What is one thing you can do?

No—take action such as reducing carbon footprint or supporting conservation efforts.