96% of marine animal species became extinct in the Permian mass extinction at the end of the Paleozoic, 252 million years ago.

How does continental drift affect living organisms See Concept 25.4 page 536?

Continental drift affects organisms by changing the current environment in all of these ways. Organisms may have to adapt, move, or go extinct. Evolution, and in particular natural selection, can only select for the best available traits.

Why do some scientists believe that RNA rather than DNA was the first genetic material See Concept 25.1 page?

Why do some scientists believe that RNA, rather than DNA, was the first genetic material? -RNA has both information storage and catalytic properties. -RNA can replicate more accurately than DNA. -All the proto-cells on early Earth contained RNA.

Why do some stickleback populations lack pelvic spines?

Why do some stickleback populations lack pelvic spines? Pelvic spines are homologous to legs in four-legged animals and freshwater sticklebacks don’t need hind limbs to move. In lakes with dragonfly larvae, pelvic spines can be disadvantageous, allowing the predatory larvae to grab the fish.

What was the oxygen revolution which took place 2.3 billion years ago?

The “oxygen revolution” was the rapid increase in atmospheric oxygen that took place 2.3 billion years ago, dooming many prokaryotic groups. The “oxygen revolution” was the rapid increase in atmospheric oxygen that took place 2.3 billion years ago, with the origin of plants.

How many periods of mass extinction have occurred quizlet?

Ordovician-Silurian extinction 444 million years ago, 86% of species lost.

How does continental drift affect ecosystems?

During continental drift, plant and animal species are most likely to evolve or become extinct because of climate change. Continents moving towards a pole means less energy from sunlight which means lower temperatures and less vegetation. Continents moving towards the equator will have a warmer climate.

How was early Earth from more than three billion years ago different from today’s Earth?

How was early Earth from more than three billion years ago different from today’s Earth? Explanation: Prokaryotes originated a few hundred million years after Earth’s crust cooled and solidified. The atmosphere of early Earth probably contained no O2 until the emergence of organisms that _____.

What is the difference between an F+ donor and an HFR donor?

What is the difference between an F+ donor and an Hfr donor? The Hfr donor has an F factor integrated into its main chromosome, but the F+ donor does not.

Why do scientists think RNA came before DNA?

RNA has great capability as a genetic molecule; it once had to carry on hereditary processes on its own. It now seems certain that RNA was the first molecule of heredity, so it evolved all the essential methods for storing and expressing genetic information before DNA came onto the scene.

Why do many scientists think that life began with RNA rather than with DNA?

Most scientists think that RNA came first, because RNA can do two jobs: store information and perform various functions that keep cells alive. This idea, that RNA came first, is called the RNA world hypothesis.

Why is RNA rather than DNA thought to have been the first genetic material?

Why is RNA, rather than DNA, thought to have been the first genetic material? The nucleotide building blocks of RNA are much simpler than those of DNA. RNA is the only genetic material of the simplest living multicellular organisms. Unlike DNA, RNA is copied without mistakes.

Why does a stickleback have 3 spins?

Three-spined sticklebacks are the intermediate host of the tape-worm Schistocephalus solidus. Infected fish become bolder and therefore more likely to be eaten be predators allowing the parasite to complete its life cycle [14,15].

Why are reduced pelvic phenotypes not observed in saltwater marine sea populations?

Why? The reduced pelvic phenotypes have never been observed in marine and sea-run populations; the pelvic spines protect marine and sea-run sticklebacks from larger fish that prey on them in the ocean.

Why do sticklebacks have less armor?

New research shows that when two species of stickleback fish evolved and lost their pelvises and body armor, the changes were caused by different genes in each species. That surprised researchers, who expected the same genes would control the same changes in both related fish.

How long does it take new species to form on Earth?

Their analysis suggests that speciation is essentially random. No matter what the life form — plant or animal, insect or mammal — it takes about 2 million years for a new species to form. Random genetic events, not natural selection, play the main role in speciation.

What evidence is there that oxygen began to build up in the Earth’s atmosphere about 2.3 billion years ago?

The answer is tiny organisms known as cyanobacteria, or blue-green algae. These microbes conduct photosynthesis: using sunshine, water and carbon dioxide to produce carbohydrates and, yes, oxygen.

How many years ago was the oxygen revolution?

The Earth’s worst mass extinction was suffered during an ocean anoxic event 250 million years ago.