BIOL 122- Organisms and Their Environment

Exam 1

Biological Evolution

Changes in allele/gene frequency over time.

“fitness” in the terms of evolution

Organism’s ability to survive and reproduce more than its population.

stabilizing selection

This is the most commonly observed form of selection, where intermediate phenotypes are more fit than extreme ones. It reduces genetic variation and maintains the status quo, as individuals with average traits have the highest survival and reproduction rates.

Directional selection

This type favors one extreme phenotype over all others, causing the population's trait distribution to shift in the direction of that extreme over time. This often occurs in response to environmental changes or new selective pressures.

disruptive selection

Also known as diversifying selection, this occurs when both extreme phenotypes are favored over intermediate values, which are selected against. This can lead to increased genetic variance and, over time, potentially the formation of two distinct groups within the population.

How would DNA be different if the hydrogen bonds were replaced with covalent bonds? Could DNA still be copied? Could genes still be expressed?

DNA could not be copied because covalent bonds can not be easily broken and put back together, so the DNA would be broken and genes could not be expressed.

What is a gene pool?

the amount of alleles available

What are the 5 mechanisms of evolution

1. Natural selection

2. Sexual selection

3. Genetic Drift

4. Immigration/emigration

5. Mutation

similar selective pressures caused the ability to evolve twice

convergent evolution

What are the essential elements for life?

C-HOPKNS CaFe Mg NaCl

Where do plants acquire the carbon that they need to generate cellulose and grow their bodies?

The Air

Who took the first visible photo of DNA?

Roseland Frankland

Intersexual selection

is "mate choice," where one sex (typically females) chooses a mate based on certain characteristics,

Intrasexual selection

is "male-male competition," where members of the same sex (typically males) compete for access to mates