deck 1

Question 1

how do dihybrid crosses explain how meiosis works?

Answer 1

Dihybrids occur because of independent assortment of chromosomes in unlinked pairs during meiosis at metaphase 1.

Question 2

what are five developmental patterns common to all multicellular organisms?

Answer 2

1.) Cell division
[E.g. Mitosis and cytokinesis]

2.) Cell-cell interaction
[E.g. Cells communicate chemically during differentiation that can cause to do all 5 developmental patterns]

3.) Cell differentiation

4.) Cell movement and changes in shapes

5.) Programmed cell death
[E.g. apoptosis]

Question 3

what is evolution?

Answer 3

the changes in allele frequency of a population over time.

Question 4

what did lamerck believe?

Answer 4

Everything arose via spontaneous generation (disproven)

• Some organisms acquired traits because of different needs and offspring inherited the characteristics (WRONG, evolution does not occur because of a need)

Question 5

what are three reasons darwin’s ideas were revolutionary?

Answer 5

1.) Overturned the idea that species are static and unchanging, and suggest that species change and are related through common ancestry

2.) His ideas replaced hypological thinking with population thinking (variation and populations matter)

3.) His ideas were scientific, they made predictions that can be verified through the scientific method. (experiments and observations)

Question 6

What are fossils?

Answer 6

Mineralized remains of organisms in sedimentary rock. Fossils are dated by superposition and radiometric dating. (NOT CARBON DATING)

Fossils are the only way scientists can examine the physical appearance of extinct forms and infer how they lived.

Question 7

What is a Synapomorphy?

Answer 7

a type of homology; a shared, derived trait.

Question 8

What is homology?

Answer 8

shared ancestral traits in species

Question 9

What is differential fitness?

Answer 9

The subset of individuals that best survives and best reproduces (high fitness) pass on their traits to offspring.

Those that lack the traits, die, and take their alleles with them.

Question 10

What are Darwin’s four postulates?

Answer 10

1.)Variation exists among individuals that make up populations

2.)Some of the traits are heritable

3.)Survival and reproduction (fitness) is highly variable

4.)The subset of individuals that survive and best reproduce is non-random, they pass on those traits that they have to their offspring.

Question 11

what is natural selection?

Answer 11

When heritable variation (in some trait) leads to differential reproductive success.

Question 12

what is fitness?

Answer 12

the number of offspring an individual has

• relative to other individuals in their population.

Question 13

what is adaptation?

Answer 13

a trait that leads to higher fitness.

Question 14

what are four modes of selection?

Answer 14

1. Directional Selection
2. Stabilizing Selection
3. Disruptive Selection
4. Balancing Selection

Question 15

What is directional selection?

Answer 15

Changes the average value of a trait.

Question 16

What is stabilizing selection?

Answer 16

Reduces variation in a trait

the center of the range has the highest fitness relative to the extremes.

Question 17

What is Disruptive Selection?

Answer 17

Increases variation in a trait

the extremes of the range have the highest fitness.

Question 18

what is Balancing Selection?

Answer 18

No one phenotype has higher fitness, maintaining variation in a trait.

Question 19

why do balancing selections occur?

Answer 19

1. Heterozygote advantage:
   Heterozygotes have higher fitness than homozygotes.
2. Environment varies over time and space
3. Frequency-dependent-selection: Fitness is dependent on how common (or uncommon) the alleles in a population are causing fluctuation.