Vertebrates and evolution
A marine biologist captures a fish whose skeleton is made entirely of cartilage rather than bone. The animal has exposed gill slits and lacks a swim bladder, requiring constant movement to avoid sinking.
What are chondrichthyans?
A vertebrate fossil shows the first evidence of four weight-bearing limbs capable of supporting movement on land rather than swimming.
What are tetrapods?
A caterpillar lives inside a leaf and eats its way through the plant tissue it lives in.
What is substrate feeding?
In the human digestive system, epithelial cells form stomach tissue, stomach tissue forms the stomach organ, and the stomach works with other organs to digest food.
What is the biological hierarchy: cells → tissues → organs → organ systems?
A stomach cell releases an inactive protein-digesting enzyme precursor that becomes active only after exposure to stomach acid.
What are chief cells?
A freshwater fish adjusts its buoyancy by filling a gas-filled internal sac and protects its gills with a movable bony flap.
What are Actinopterygii (ray-finned fishes)?
A reptile embryo develops inside an egg containing membranes that protect it from drying out and allow development on land.
What are amniotes?
A whale swims with its mouth open, allowing seawater to pass through comb-like plates that trap krill while water exits.
What is suspension feeding?
A student analyzes where most chemical digestion and nearly all nutrient absorption occur in the human digestive system.
What is the small intestine?
A patient has reduced stomach acidity and impaired protein digestion due to damage to the cells that produce hydrochloric acid.
What are parietal cells?
A fish remains still while pumping water over its gills because a bony flap covering the gill chamber helps move water across respiratory surfaces.
What is the operculum?
Scientists believe that vertebrates were able to colonize land when this evolutionary innovation allowed embryos to develop outside water without drying out
What is the amniotic egg
An earthworm consumes soil and extracts organic nutrients left behind by decomposing organisms.
What is deposit feeding?
Removal of this organ would reduce the body’s ability to efficiently emulsify fats during digestion.
What is the gallbladder?
This enzyme breaks starch into smaller sugar molecules during digestion.
What is amylase?
A fish living at different depths in a lake maintains neutral buoyancy without constant swimming by regulating gas in an internal sac
What is a swim bladder?
The discovery of lobe-finned fish fossils with bone structures similar to early limbs suggests these organisms were the evolutionary ancestors of this vertebrate group.
What are tetrapods?
A butterfly uses a long coiled proboscis to drink nectar from flowers. / A mosquito pierces the skin of a host and extracts blood using specialized mouthparts.
What is fluid feeding?
Besides digestive enzymes, this organ releases bicarbonate to neutralize acidic chyme entering the small intestine.
What is the pancreas?
After partial digestion in the stomach, proteins are further broken down into amino acids in this organ by pancreatic enzymes.
What is the small intestine?
A fossil fish is discovered with thick, muscular fins containing bone structures similar to the limbs of early land vertebrates.
What are Sarcopterygii (lobe-finned fishes)?
A human bites, chews, and swallows pieces of food that are later broken down by enzymes in the digestive tract.
What is bulk feeding?
DNA and RNA from food are broken down in the small intestine by these pancreatic enzymes.
What are nucleases?