BIOLOGY LAB PRACTICUM II

Embryology

The branch of biology that focuses on the study of development following fertilization

Fertilization

Union of gametes, the sperm and the egg

Are gametes haploid or diploid?

Haploid

Haploid

Cells that carry half the normal complement of chromosomes

Diploid

Cells with a complete set of genetic information

Mitosis produces first __ cells, then __

2, 4

Name A through I.

A. Oocyte, B. zygote C. metaphase, D. two, E. four, F. eight, G. morula. H. blastocyst, I. blastocyst

Name A, B, and C.

A. fallopian tube, B. Ovary, C. uterus

How many days does it take for the early embryo to travel from the time it leaves the ovary to the uterus?

5 days

Radial symmetry

Body parts radiate outward from a central point or pivot axis; commonly found in organisms such as jellyfish and starfish.

bilateral symmetry

organisms that could be sliced in half, and each part would be a mirror image of the other.

By the time the embryo reaches the gastrula stage, cells have differentiated and formed 3 germ layers: ___, ___, and ___.

the ectoderm, the mesoderm, and the endoderm

What structures develop from the ectoderm?

skin and nervous system

What structures develop from the mesoderm?

Muscles, bones, blood, heart, kidneys, connective tissues

What structures develop from the endoderm?

Liver, pancreas, lungs, thyroid

What comes after gastrulation and what is the process called?

Neurulation: formation of the neural tube, which becomes the brain and spinal cord.

What happens during neurulation?

During neurulation, the ectoderm forms the neural plate, which folds into the neural groove and then closes to form the neural tube, which develops into the brain and spinal cord.

Name A, B, and C

neural groove, notochord, gut

Which letter indicates the gut?

C

Which letters indicates the ectoderm, mesoderm, and endoderm?

B. ectoderm, D. mesoderm, E. endoderm

Why is the yolk sack in a bird embryo larger than in a human embryo?

Because they primarily draw their nutrients from the yolk sack while human embryos draw from the placenta.

Where does fertilization usually occur?

fallopian tube

Describe the layers of the gastrula

innermost = endoderm, middle = mesoderm, exterior = ectoderm

What structure in the developing embryo becomes the brain?

Anterior end of the neural tube

What structure in the developing embryo becomes the spinal chord?

Posterior neural tube

How long after fertilization is the developing baby considered a fetus?

After 8 weeks

What is the developing baby called priori to becoming a fetus?

Embryo

Name the cell stages

1. zygote

2. blastula

3. 2-cell stage

4. gastrula

A solid ball of cells in the early stages of development describes the ___.

morula

a zygote is ___.

a fertilized egg.

a blastula is___.

a hollow mass of cells

The gastrointestinal tract, intestines and esophagus develop from the___.

endoderm

The skin, hair, and nervous system are derived from the ___.

ectoderm

What type of symmetry is this?

Radial

What type of symmetry is this?

bilateral

Which letter is pointing to a starfish larva?

D

In humans, fertilization usually occurs in the ___.

fallopian tube

Approximately how long does it take for the egg to travel from the ovary to the uterus?

5-6 days

Populations

groups of individuals of the same species living in the same area.

Population size ___ over time.

changes

Exponential population growth

the number of individuals increases at a constant percentage rate over time, causing the population to grow larger and larger more rapidly (J-curve)

Population growth rate formula

r = birth rate - death rate

Carrying capacity

the number of individuals the environment can support

The simplest model that includes the carrying capacity

logistic growth (S-curve)

Maximum sustainable yield

the maximum amount of resources that can be extracted sustainably over the long term

Calculating variance

Variance = (sum of squared differences from the mean) / (n − 1)

Calculate standard deviation

Standard deviation = sqrt(variance) = sqrt[(sum of squared differences from the mean) ÷ (n − 1)]

The time it takes for the population to double in size

Doubling time

Average profit = $112.50

Variance ≈ 491.67

Standard deviation ≈ 22.17

Define evolution

the change in organisms across generations

Evolution is natural selection. True or false?

False

Observations that backed natural selection:

1. variation

2. heritability

3. struggle for existence

   1. characteristics = ability to survive and reproduce

Conclusions of Wallace and Darwin’s observations

Populations will change and adapt over time as individuals with well-suited traits survive and reproduce, passing down the well-suited traits for future survival

Natural selection is random. True or false?

False

What happened to the peppered moth population before and after the Industrial Revolution?

Before: Light-colored moths were more common.

After: Dark-colored moths became more common because pollution darkened the trees.

Endemic species

native species that do not exist anywhere else

Allopatric speciation

formation of new species in geographic isolation

What is morphology?

The study of physical characteristics (body structure) used to compare species and infer evolutionary relationships.

What does a shared derived trait suggest?

Species with the same derived trait likely share a more recent common ancestor.

What is an ancestral trait?

A trait inherited from an older ancestor and shared by many species.

What is a derived trait?

A newer trait that evolved after a species diverged from its ancestors.

What does the cranial index measure?

Braincase width relative to face width.

High cranial index = larger braincase relative to face.

What does the facial extension index measure?

How far the face/jaw projects forward.

Higher value = more protruding face.

What is the dental formula?

The number and types of teeth on one side of the mouth.

What do brow ridges indicate?

The size of the ridge above the eyes.

Larger ridge = more pronounced brow.

What is a sagittal crest?

A ridge on top of the skull for jaw muscle attachment.

Large crest = powerful chewing muscles.

What does the frontal bone describe?

The slope of the forehead.

Vertical = flatter forehead

Sloping = forehead angles backward

What does the canine-incisor index measure?

Canine size relative to incisor size.

Higher value = larger canines.

What does the foramen magnum indicate?

Where the spinal cord enters the skull.

More forward position = more upright posture/bipedalism.

What does relative brain size measure?

Brain size compared to body size.

what do the parts of the phylogenetic tree describe?

Branch tip s= species, nodes where branches separate = speciation events (formation of a new species), notes between branches = evolutionary changes

fossils

the remains of organisms that existed long ago

How do fossils form?

An organism dies, is buried by sediment, and over time the remains or impressions are preserved as rock.

What is a trace fossil?

Fossil showing activity: footprints, tracks, nests, etc.

What are the three eras of the Phanerozoic Eon?

Paleozoic, Mesozoic, Cenozoic

When did the Paleozoic Era begin and end?

Started: 541 million years ago

Ended: 252 million years ago

When did the Mesozoic Era begin and end?

Started: 252 million years ago

Ended: 66 million years ago

When did the Cenozoic Era begin and end?

Started: 66 million years ago

Ended: Present

Which era is known as the "Age of Reptiles"?

Mesozoic Era

Eras are divided into…

Periods

What are the three periods of the Mesozoic Era?

Triassic, Jurassic, Cretaceous

What marks the transition from one period or era to another?

Mass extinctions and the appearance of new species.

What is a mass extinction?

An event in which more than 50% of species disappear.

What was the largest mass extinction in Earth's history?

Permian–Triassic extinction

When did the Permian–Triassic extinction occur?

252 million years ago

Front: What is the K–T (now K–Pg) extinction?

The mass extinction that wiped out the non-avian dinosaurs.

When did the K–T (K–Pg) extinction occur?

66 million years ago

What is a “missing link”?

transitional fossils in the fossil record that have not been found or don’t exist

Natural selection, mutation, genetic drift, migration

The two biologists that independently developed the theory of natural selection:

Alfred Wallace and Charles Darwin

The evolution of several species of pupfish in the Death Valley region is an example of what type of speciation?

Allopatric speciation

What factors are required for allopatric speciation? List the 2 most important.

i. Geographic isolation (physical separation)

ii. Genetic divergence (different mutations/natural selection over time)

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10) Name the 3 eras from oldest to most recent.

i. Paleozoic

ii. Mesozoic

iii. Cenozoic

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11) A graph that shows the evolutionary relationships between species is called a(n)

✅ Phylogenetic tree

Geographic isolation and genetic divergence

Name the 3 eras from oldest to most recent.

paleo, meso, ceno

A graph that shows the evolutionary relationships between species is called a(n)

phylogenetic tree

Most plants are…

angiosperns

Key characteristics of Kingdom Plantae; plants…

1. have cells with cell walls made of cellulose

2. store energy as starch

3. use chlorophyll b, the pigment for photosynthesis

4. provide support for the developing embryo in early development

plant evolution main challenges

dehydration and reproduction without water