Exam 1

Question 1

List the steps of the scientific method.

Answer 1

Question - the problem that needs solving

Hypothesis - potential answers to the question based on prior knowledge and experience

Experiment - collected data used to prove or disprove hypothesis

Observation - knowledge acquired through the sense (touch, smell, appearance) or scientific equipment

Analysis - comparing results of experiment to the hypothesis

Conclusion - statement saying whether hypothesis is supported or refuted by the observation

Question 2

Distinguish between a hypothesis and a theory.

Answer 2

Hypothesis - reasoned and informed explanation

Theory - broad range of explanations for phenomena supported by a large sum of evidence

Question 3

List some important characteristics of science (compared to philosophy, theology, history, or other non-scientific ways of studying the world).

Answer 3

Quantitative - Metric System
Repeatable - experiment can be done over and over again
Objective - Unbiased
Cumulative
Self-correcting
Naturalistic/Materialistic - Science is about matter and energy

Question 4

Explain the four steps proposed for the origin of life from non-life.

Answer 4

1. The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nitrogenous bases.
2. The joining of said small molecules into macromolecules, such as proteins and nucleic acids
3. The packaging of macromolecules into protocells (droplets that maintain different internal chemistry from their surroundings)
4. The self-replicating molecules that eventually made inheritance possible.

Question 5

Explain two reasons why the four steps proposed for the origin of life would be difficult or impossible today.

Answer 5

1. The environment we live in makes it near impossible for the early molecules to survive. Mainly because if these molecules were to occur spontaneously, they would be immediately attacked by O2.
2. There is already life on earth. So if an organic marcomolecule showed up due to spontaneous processes, it would get eaten by some living thing before it had a chance to become part of a living life form.

Question 6

List three reasons that RNA rather than DNA is hypothesized to be the first genetic molecule.

Answer 6

Shape diversity
Catalysis
Self-replication

Question 7

Explain Steno’s laws and other major principles of historical geology.

Answer 7

Principle of Superposition- old rock is on the bottom, new rock is at the top

Principle of Original Horizontality- sediment is deposited in flat, horizontal layer

Principle of Original Lateral Continuity- sediment deposited on seafloor extends a large distance in all directions

Principle of Intrusive Relationships- Sedimentary rocks are older than igneous rock that intrudes into them

Principles of Fossil Succession- Fossils occur in a consistent vertical order in sedimentary rocks all over the world.

Question 8

List the eras of the geological time scale and the ages of the boundaries between them

Answer 8

1. (545 mya) Paleozoic: Cambrian Explosion; Reptiles and amphibians appear
2. (251 mya) Mesozoic: Age of Dinosaurs
3. (65 mya) Cenozoic: Age of Mammals

Question 9

List the periods of the geological time scale associated with dinosaurs

Answer 9

Jurassic - dinosaurs dominated
Triassic - dinosaurs still dominated
Cretaceous - they died out

Question 10

Explain how C-14 is formed, accumulates in organisms, and decays.

Answer 10

Cosmic rays from sun enter earth’s atmosphere and collide with atoms and creates neutrons; these neutrons then collide with N-14 and changes it to C-14; plants absorb C-14 through photosynthesis; animals and people then eat plants and take in C-14; when they die C-14 changes back into N-14 by beta decay

Question 11

Explain what sort of materials can be aged using C14.

Answer 11

It must be organic (we can’t use it on volcanic rock or sedimentary rock) but we can use it on bones, mummified soft tissue, etc. And it must have died in the last 40,000 years or so to get a very accurate age estimate.

Question 12

State how many mass extinctions are known, and what evidence supports them.

Answer 12

There are five documented mass extinctions. What support’s them is the nearly completed fossil records that date back to the time of the mass extinctions

Question 13

State the best-supported hypothesis for the extinction of the dinosaurs. Identify evidence that supports this hypothesis.

Answer 13

The best-supported hypothesis for the extinction of dinosaurs is that a giant asteroid or comet collided with the earth. Proof of this is a thin layer of clay enriched with iridium that dates back to the extinction (about 65 million years ago). Iridium is a rare find on earth but is common meteorites.

Question 14

List two features that contrast multicellularity with simple colony formation.

Answer 14

reproductive cells

cell specialization

Question 15

List three major challenges of multicellular bodies.

Answer 15

cell communication
cell organization
cell reproduction

Question 16

Identify solutions to the challenges of cell adhesion

Answer 16

The Extra Cellular Matrix and associated proteins help cell

Question 17

Describe support structures found within and between cells of multicellular organisms.

Answer 17

Skeletons provide support at the multi-cellular level (bone, shell, exoskeleton, hydrostatic skeleton, etc.) and at the cellular level we have a cytoskeleton that provides support. Those large-scale support structures are often just specialized extra-cellular matrix.

Question 18

Define animal in terms of cell support.

Answer 18

multicellular organisms that has an ECM of collagen and elastin

Question 19

Define tissue.

Answer 19

an organization specialized cell

Question 20

List three functions of a skeleton.

Answer 20

support, protection, movement

Question 21

Define homeotic gene.

Answer 21

regulatory gene that controls pattern of body formation during early embryonic development of organisms

Question 22

Describe the arrangement of homeotic genes on chromosomes.

Answer 22

HOX genes are arranged on a chromosome in head-to-tail order. So the genes that control development of the front part of the body are at one end, and then they are in body order all the way to genes that help control development of the back legs and tail.

Question 23

Explain the importance of cell signaling in multicellular organisms.

Answer 23

Cell signaling is important because cells of different types have to talk to each other for a multi-cellular organism to function

Question 24

Identify some molecule types involved in cell signaling.

Answer 24

Neurotransmitters, hormones and protein transmitters

Question 25

Explain how cancer can be thought of as a disorder of cell signalling and cell adhesion.

Answer 25

Cancer is unregulated cell signaling, and cells need to divide when it makes sense (in terms of body function). So, it’s important for cells need to know when to NOT divide in order to prevent tumors. And cell adhesion keeps tumors together in one place because failure of adhesion leads to metastasis - cancers that spread.

Question 26

Explain the hypothesis of the role of symbiosis in multicellularity.

Answer 26

One hypothesis for multicellularity is that cell cooperation is necessary for multicellularity much like it is in symbiosis or endosymbiosis. For cells to specialize they must turn some genes on or off. In mutualism, cells (or species) depend on each other to do specialized jobs. Mitochondria and chloroplasts are and example. Their ancestors were free-living single celled bacteria, but they moved into larger eukaryotic cells and began to cooperate (specialize).

Question 27

Define heterochrony and paedomorphosis.

Answer 27

Heterochrony- change in timing or rate of an organism’s development

Paedomorphosis- retention in an adult organism of the juvenile features of its evolutionary ancestor

Question 28

Define homeotic gene.

Answer 28

master regulatory gene that controls placement and organization of body parts in animals, plants, and fungi. It does this by controlling the development of groups of cells while the organism is an embryo.

Question 29

List examples of homeotic gene comparisons between species

Answer 29

1. Homeotic genes regulate development by turning on families of genes (for example, all the genes to develop a leg) at the right place and time.
2. Homeotic genes are organized on a chromosome – head genes toward one end of the chromosome, tail or foot genes toward the other end.
3. Animals share homologous homeotic genes (fruit fly genes are very similar to human genes due to descent from a common ancestor).
4. Animals that are more “advanced” may have duplicated genes. For example, fruit flies have homeotic genes on one chromosome, but mammals have duplicated that to four sets of homeotic genes.

Question 30

List examples of homeotic gene malfunctions.

Answer 30

Homeotic gene malfuncitons often pbserved in fruit-flies. The homeotic gene that codes for legs sometimes puts it on the antennae.

Question 31

List and explain the major observations/facts and the logical deductions that form the foundation of Darwin’s theory.

Answer 31

1. The striking ways in which organisms are suited for life in their environments
2. the many shared characteristics(unity) of life
3. the rich diversity of life
   Facts: fossils turn up where similar animals live in current times; the tree of life( all species come for older extinct species); species give rise to other slightly different species( decent with mods)

Question 32

Explain the phrases “survival of the fittest,” “descent with modification,” “natural selection,” and “differential reproduction.”

Answer 32

1. survival of the fittest: In Darwinian terms, it means the ability to produce offspring
2. descent with modification: over the generations small changes accumulate, so that the descendants are quite different from their ancestors many generations ago
3. natural selection: process in which an organism with certain traits tend to survive and reproduce than other organisms because of their traits
4. differential reproduction: the idea that those organisms best adapted to a given environment will be most likely to survive to reproductive age and have offspring of their own

Question 33

Contrast analogy vs. homology.

Answer 33

For analogy, similarities between two species is because of convergent evolution rather than decent from a common ancestor.
For homology, similarities in characteristics is from a shared ancestry

Question 34

Explain how anatomical homologies and vestigial structures support Darwin’s theory. Discuss molecular homologies in this context.

Answer 34

Anatomical homologies are evidence of common descent. For example, hippos and a camels both have pulley-shaped ankle bones.This is because their common ancestor had pulley-shaped ankles, and since they are both descendants of that ancestor, both inherited the trait.
Vestigial structures are appendages that an organisms no longer uses but natural selection can’t completely get rid of it. For example, snakes have claws that use to be part of their legs. This is because over time, selection favored the ancestors that walk less and less. Also, selection can’t completely get rid of it because it still has a function( snakes use them to attract mates).
Molecular homologies works the same way as anatomical structures. Organisms(in this case whales and hippos) inherited their jumping gene pattern from a common ancestor.