Chargaff was able to show the diversity of DNA through patterns within base pairs. While studying DNA, he noticed that the concentration of adenine was equal to the concentration of thymine, and the concentration of cytosine was equal to that of guanine. This led him to establish Chargaff’s rules, which state that the base composition of DNA varies between species, and for each species the percentages of adenine and thymine bases are roughly equal and the percentages of cytosine and guanine are also roughly equal.

Thomas Malthus was a political/economic theorist who observed that the human population would eventually overpopulate the world, overwhelming food and natural resources. 

Mitochondria and chloroplasts are believed to have evolved from prokaryotic cells over 1.5 million years ago. This is known as the endosymbiotic hypothesis. Mitochondria, chloroplasts, and prokaryotes all contain circular DNA and reproduce via binary fission. Mitosis involves the separation of chromosomes during the cell cycle, which is only seen in the somatic cells of eukaryotes. Meiosis is not seen in prokaryotes. 

Lamarck incorrectly believed that parents could pass on traits that they had acquired to their offspring. He believed that the changes made during a lifetime, such as increased muscle mass, would be passed on to offspring. This is not true since acquired traits, except on very few rare occasions, do not affect the DNA. For example, if two parents have small muscles, but then take steroids and become bodybuilders, their offspring will still inherit the small muscle genes, since only the muscles, not the DNA is affected by bodybuilding.

It is believed that sponges were the first animals to utilize multicellularity. Sponges only have a few cell types, including: choanocytes, porocytes, and pinacocytes. Choanocytes have flagella that beat continuously to move water, and microvilli, which are specialized for absorbing nutrients. Porocytes are tubular cells that form the pores of sponges. Pinacocytes produce collagen and provide structural support to the sponge. Although algae likely developed multicellularity early on, they are not animals. Arthropods and mammals are both multicellular and animals, but evolved after sponges.

Coprolites are fossilized fecal matter from an animal. By studying their contents, biologists can gather information on what the animal ate, and what species were there to be eaten by the animal.

The key to answering this question is organic material. Once an organism dies, it ceases to participate in carbon exchanges with the atmosphere. What carbon is left in the organism then decreases at a stable rate which allows scientists to reliable date the era that the organism died in.

When a thermal neutron collides with a nitrogen atom in the atmosphere, it causes a proton to fly off from the atom, reducing the atom from nitrogen to carbon while keeping the same number of neutrons, 14. Because the amount of matter in the universe is believed to be constant, we can measure the amount of carbon-14 left in a dead specimen to determine its age within approximately 50,000 years.

Carbon-14 dating is used to date organic material within an approximately 50,000 year time period, due to the relatively short half life of the carbon-14 isotope. Other isotopes are used to date the rocks surrounding dinosaur fossils, such as in the uranium-lead method or the potassium-argon method.

Structures that are similar as a result of convergent evolution are referred to as analogous structures, such as the wings of beetles and birds. These animals do not share a common ancestor, and developed the trait for wings independent of one another. Homologous structures arise when two organisms share a trait due to linkage with a common ancestor. For example, legs of a dog and the legs of a cat are considered homologous.

Phylogeny refers to the evolutionary history of a lineage, and can be used to identify common ancestors. Taxonomy is the naming and classification of organisms. Binomial nomenclature is the scientific name for an organism containing its genus and species.