Unit 9 Bio

Why can organisms decode the information in each other's genes?

Organisms can decode the information in each other's genes because DNA and protein synthesis are shared core processes between organisms, allowing a gene from one organism to be decoded and expressed by another.

List three types of information you could get from reading a tree diagram.

Three types of information you could get from reading a tree diagram are seeing how different species are connected and linked (relatedness), determining what the most primitive characteristic between connected organisms is, and analyzing traits that separate organisms from others.

How is it possible that the gene for the luciferase protein can be expressed in mice?

It is possible for the gene for the luciferase protein to be expressed in mice because all organisms share the genes that code for cellular transcription and translation machinery. Both mice and fireflies use the A, C, G, and T building blocks that form DNA, meaning they can read the gene sequence and it will function the same way.

Describe the anatomical evidence that shows that Cetaceans are more closely related to mammals than fish.

Cetaceans and mammals both have internal skeletons, are warm-blooded, have lungs, give live birth, have mammary glands/milk, and have a 4-chambered heart. On the other hand, cetaceans and fish only share that they both have internal skeletons.

Describe the fossil evidence that shows that cetaceans are the descendants of an animal that lived on land.

50 million years ago, an organism called the pakicetus moved on land and had small attachments for tail muscles, nostrils, ears that could somewhat hear in water but better in air, and hooves. Over time, these features slowly adjusted to be more suited for water, and have slowly evolved into the modern orca, which has nostrils, ears well suited for hearing underwater, powerful tail muscles anchored to the spine, and internal femur bones.

Describe the embryological evidence that shows that cetaceans are the descendants of an animal that lived on land.

At the beginning of dolphin embryo development, it has a hindlimb. However, as it undergoes more development and grows, the hindlimb slowly becomes hidden. The position of the dolphin's nostrils also moves from a lower part of the head to a higher part of the head.

Describe the DNA evidence that shows that cetaceans are most closely related to the hippopotamus.

In hippopotamus, the number of amino acids that differ from whale casein is only 24 out of 145, making them 83.4% identical to whale casein overall.

How do mutations and allele shuffling increase variation within a population?

Mutations and allele shuffling increase variation within a population because it allows an organism's DNA to be unique from the others, and also allows the species to have a better chance of survival overall. Different alleles produce different genotypes and phenotypes of the same gene, and random base changes in the DNA sequence cause organisms to have different characteristics and therefore increase variation.

Are all gene variations beneficial? Explain why or why not.

Not all gene variations are beneficial, because some can cause harm to an organism and some can have no effect on an organism at all. For example, a bird unable to see color is harmful for them, and minor changes in pattern on an organism's fur or skin causes them no harm but also does not help them in any way.

Give an example from the lab of how an organism can be more fit in some environments than others?

In the environment with spaghetti as the food source, the forceps could easily pick up the thin sticks of spaghetti, while the toothpick couldn't pick up anything, demonstrating that the forceps are more fit in that environment than the toothpick is.

What is evolution?

Evolution is any change in the heritable traits within a population across generations.

Small Population

The population can shrink and the gene pool is small

Non-random mating

Frequency can change depending on who mates with who

Mutation

If a new gene is added through mutation the frequency can change

Gene Flow

If individuals flow in or out of an area, the frequency can change

Natural Selection

Some traits may have an advantage or disadvantage, and the frequency will change depending on the environment

How does natural selection cause populations to become better adapted to their environments?

Natural selection causes populations to become better adapted to their environments because those with the advantageous trait will continue surviving and reproducing, while those with the disadvantageous trait will die off. This means that over time, those with the advantageous trait will become much more common and well adapted to the environment.

What increases genetic variation within a population?

Sexual reproduction, meiosis, and heritable mutations increase genetic variation within a population.

Provide two examples of environmental pressures.

Population and food resources are two examples of environmental pressures.

Heritable Traits in relation to peppered moths

The trait of darker coloration in peppered moths is heritable, so it was passed down to offspring as more of them survived during the industrial revolution compared to the light peppered moths.

Struggle for Survival in relation to peppered moths

When the industrial revolution happened, more dark colored peppered moths survived because they could blend in with the soot-covered trees rather than the light colored peppered moths.

Genetic Variation in relation to peppered moths

The genetic variation of darker coloration for peppered moths allowed them to survive more easily during the industrial revolution.

Reproductive Advantage in relation to peppered moths

More of the darker colored peppered moths survived, so they reproduced together, and passed down the trait to their offspring.

What is fitness (*note: this is not the same thing as physical fitness)?

Fitness is a measure of an organism's ability to survive and produce offspring relative to other members of a population.

Does natural selection lead to changes in individuals OR changes in populations? Explain.

Natural selection leads to changes in populations because organisms with a disadvantageous trait will die out, while organisms with an advantageous trait will increase their population. For example, if an extremely common trait suddenly becomes disadvantageous, the population may almost die off completely, but those with the much rarer version of the trait that is also advantageous will allow the population to grow and increase eventually.

Explain how and why the rock pocket mouse population changed over time after the lava flow turned the desert floor black.

After the lava flow turned the desert floor black, the light colored mouse population started to decrease, while the dark colored mouse population began to increase. This is because it is much easier for a dark colored mouse to blend in with its surroundings and hide from predators in a dark environment, so more of them survive than the light colored mice.

Explain how mutation is a random event but natural selection is not random.

Mutation happens because of an error in the DNA code, during meiosis and sexual reproduction, and cannot be predetermined. On the other hand, natural selection happens because one trait is more advantageous than another in a specific environment, and the disadvantageous trait slowly dies out over time because the organisms with the advantageous trait are able to survive more easily through hiding from predators, finding food easier, etc.

Name and describe the three "ingredients" necessary for natural selection.

Variation means that for a certain trait, there are differences between individuals. Heritability means differences come from genes passed from parents to offspring. Reproductive Advantage means individuals with a certain trait are more successful at reproducing than others.

Explain how and why the stickleback fish population changed when the fish moved from saltwater to freshwater.

The stickleback fish population changed when the fish moved from saltwater to freshwater because the trait of low armored plates started to appear much more often, rather than a high number of armored plates, which is what the saltwater sticklebacks had. This is due to low armor being a better trait for survival from predators in the freshwater area, as these sticklebacks have different predators than the saltwater ones.

What does a normal distribution graph look like?

Both sides of the graph are even (pretend there's a line in the middle)

Stabilizing

Babies of low weight lose heat more quickly and get ill from infectious diseases more easily, and babies of large body weight are more difficult to deliver leading to health complications. This means that the intermediate birth weight is favored.

Directional

Originally more moths were light colored but the trait became unfavorable due to the Industrial Revolution so dark colored moths survived and now dark coloring is a more favorable trait.

Disruptive

White fur rabbits and black fur rabbits are able to camouflage with rocks, but gray fur will not and will be more likely to be eaten by predators. Therefore, white and black fur rabbits will increase, and gray will decrease.

Which type(s) of selection can lead to the formation of a new species? Explain.

Disruptive and directional selection can lead to the formation of a new species because disruptive selection is when both extremes are favored, causing the intermediates to die out, potentially leading to separate species, and directional selection can cause the originally advantageous phenotype to die out and the newly advantageous phenotype to survive, potentially forming a new species.

What is a species?

Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.

List three factors that help determine if two organisms are the same or different species.

Behavior, what habitat they live in, what foods they eat

What is speciation?

Speciation is the rise of two or more species from a single existing species.

What is reproductive isolation?

Reproductive isolation occurs when members of different populations can no longer mate successfully. It is the final step of becoming a separate species.

Geographic barrier

The physical separation of two or more populations can lead to speciation through geographic isolation.

Behavioral barrier

Behavioral isolation is caused by differences in courting or mating behaviors. If two populations do not use the same mating behaviors, then mating and gene flow between two groups is unlikely to occur, and therefore natural selection acts upon the different gene pools. Reproductive isolation and speciation may eventually occur.

Temporal

Temporal isolation occurs when timing prevents reproduction between populations. Speciation from a common ancestor occurred as the overlap in meeting seasons shrank.

In detail, describe how to properly streak a bacteria plate. Insert an image of a properly streaked plate.

First, divide the plate into three sections. Locate an isolated colony of bacteria to use. Sterilize your bacterial loop with a flame and let it cool for about 20 seconds. Remove the bacteria sample by gently scooping up the isolated colony. Use the clamshell method to ensure contamination does not occur. Use a zig zag motion in each of the three sections, only going across once, without pressing down too hard on the agar to spread out the bacteria sample. Flame the loop in between each section. Incubate the plate upside down at 37 degrees celsius for 24-48 hours to finish the process.

What is a pure culture?

A pure culture is one kind of bacteria, free of any contamination.

How do we measure the effective distance and what does it tell us?

We measure the effective distance, the bacteria-free zone around each anti-bacterial agent, using a metric ruler. This tells us how effective the substance on the paper disc is at preventing the growth of bacteria.

Explain how antibiotic resistance occurs using the conditions for natural selection.

Antibiotic resistance occurs using the conditions for natural selection because the trait for resistance is heritable, bacteria that do not have the mutation won't be able to survive for as long as those that do have the trait, some bacteria are resistant while some are not, and bacteria with a higher resistance to antibiotics are more likely to survive and reproduce.

Describe the main causes of antibiotic resistance.

The main causes of antibiotic resistance are overuse, underuse, and misuse. Overuse is when antibiotics are used to treat infections that are not bacterial, where they are basically useless. Underuse is when the entire prescribed amount of antibiotics are not taken. Misuse is when antibiotics are used for the wrong purposes, or used in a way that can make the bacteria become resistant much more quickly and easily.