Bio Lab Midterm

Phylum: Porifera | Visible traits: asymmetry, pores (holes)

Phylum: Cnidaria | Visible traits: radial symmetry, medusa (bell shape)

Phylum: Cnidaria | Visible traits: radial symmetry, polyp form (attached)

Phylum: Mollusca | Visible traits: hard shell, soft body inside

Phylum: Mollusca | Visible traits: soft body, tentacles, no visible shell

Phylum: Annelida | Visible traits: segmented body (rings)

Phylum: Arthropoda | Visible traits: exoskeleton, jointed legs

Phylum: Echinodermata | Visible traits: pentaradial symmetry (5 arms)

Echinodermata (sea cucumber) identification

Phylum: Echinodermata | Visible traits: elongated soft body

Chordata identification

Phylum: Chordata | Key trait: backbone (not always visible)

Total magnification formula

total magnification = ocular × objective

If ocular = 10x and objective = 40x, total magnification?

400x

What happens to field of view when magnification increases?

decreases

What happens to working distance when magnification increases?

decreases

What happens to brightness when magnification increases?

decreases

What happens to detail when magnification increases?

increases

Why must you calibrate ocular micrometer?

scale changes with magnification

Depth of field definition

how much of specimen is in focus at once

RBC vs WBC

RBC: no nucleus | WBC: nucleus present

Plant cell (Elodea) features

cell wall, chloroplasts, rectangular shape

Onion cell features

cell wall, NO chloroplasts

Cheek cell features

nucleus, no cell wall

Paramecium features

cilia, oval shape

Amoeba features

pseudopods, irregular shape

Euglena features

flagellum, chloroplasts, eyespot

What determines diffusion rate?

concentration gradient, temperature, molecule size

Why did diffusion slow over time?

concentration gradient decreased

Which diffuses faster: gas or liquid?

gas (higher energy, faster movement)

Effect of temperature on diffusion

higher temp = faster diffusion

3 factors affecting membrane crossing

size, charge, polarity

Which molecules cross membrane easily?

small, nonpolar, uncharged

Simple diffusion definition

movement directly through membrane (no protein)

Facilitated diffusion definition

movement through protein channels

Osmosis definition

diffusion of water across membrane

Direction of osmosis

hypotonic → hypertonic

Hypertonic solution effect on cell

cell shrinks

Hypotonic solution effect on cell

cell swells (turgid in plants)

What is semipermeable?

only some substances can cross

Dialysis tubing experiment conclusion

small molecules pass, large (starch) do not

Why did solution turn blue (iodine + starch)?

iodine diffused in and reacted with starch

Why did mass increase in dialysis bag?

water entered via osmosis

Elodea in hypotonic solution

turgid, membrane pressed against wall, chloroplasts spread

Elodea in hypertonic solution

plasmolysis, membrane pulls away, chloroplasts clump

Plasmolysis definition

membrane pulls away from cell wall due to water loss

Potato in hypotonic solution

gains mass (water enters)

Potato in hypertonic solution

loses mass (water leaves)

Isotonic solution

no net water movement

Turgor pressure

pressure from water pushing membrane against cell wall

Hardy-Weinberg equation (alleles)

p + q = 1

Hardy-Weinberg equation (genotypes)

p² + 2pq + q² = 1

What is p?

dominant allele frequency

What is q?

recessive allele frequency

What is p²?

homozygous dominant

What is q²?

homozygous recessive

What is 2pq?

heterozygous

If given recessive phenotype, what do you set it equal to?

q²

Steps to solve HW problems

q² → sqrt = q → p = 1 - q → plug into equations

When does evolution occur?

when allele frequencies change

5 conditions for HW equilibrium

no mutation, random mating, no selection, large population, no migration

Definition of evolution

change in allele frequency over time

Population definition

group of same species in same area

Variation definition

differences in traits within population

Genotype definition

genetic makeup (alleles)

Phenotype definition

observable trait

Natural selection definition

environment favors certain traits

Fittest definition

highest survival and reproduction

Adaptation definition

trait that increases survival

Environment role in evolution

determines which traits are favored

What happens to favorable alleles?

increase in frequency

What happens to unfavorable alleles?

decrease in frequency

Why did F allele increase in rabbit lab?

fur provided survival advantage

Why did f allele decrease?

no-fur rabbits died before reproducing

Final conclusion of natural selection lab

allele frequencies changed → population evolved