FINAL BIOLOGY BOSS Flashcards
(277 cards)
1
Q
A hypothesis is
A
a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.
2
Q
The role of a control in an experiment is to
A
provide a basis of comparison to the experimental group.
3
Q
Introduced Oryx populations at White Sands Missile Range are very successful. Which of the following is NOT a hypothesis that might lead to an experiment that might explain this phenomenon?
A
Researchers found that the diet of the Oryx is different after the introduction, implying they have
4
Q
A dependent variable is
A
the variable that is the result.
5
Q
Cells spend most of their cell cycle in which phase?
A
Interphase
6
Q
The genetic material is duplicated during?
A
The S phase
7
Q
During which phase of meiosis do the chromosomes line in the middle of the cell?
A
metaphase
8
Q
Two chromosomes in a nucleus that carry the same genes in the same positions on the chromosome but may have different versions of some traits constitute a pair of:
A
homologous chromosomes.
9
Q
The products of meiosis 1 are
A
two genetically different haploid cells.
10
Q
Which below best describes a difference between a chromosome and a gene?
A
A gene is one section of a chromosome but a chromosome carries many genes.
11
Q
A diploid, somatic cell from an organism has 40 chromosomes. How many chromosomes would be in a haploid gamete from this organism?
A
20
12
Q
How many pairs of autosomes do humans have?
A
22
13
Q
A photograph of a person’s chromosomes lined up by homologous pairs and size of chromosomes is called a:
A
karyotype
14
Q
DNA replication occurs
A
In the S phase of interphase
15
Q
Chromosomes of diploid organisms that are NOT involved in sex determination are called
A
autosomes
16
Q
When we say that an organism is diploid, we mean that
A
its cells have two of each type of chromosomes
17
Q
Independent orientation of chromosomes at metaphase I results in an increase in the number of
A
possible combinations of chromosomes in gametes.
18
Q
What is the typical result when a diploid cell undergoes meiosis?
A
four haploid cells
19
Q
In a cell containing 10 chromosomes, meiosis results in the formation of ____ daughter chromosomes.
A
5
20
Q
In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing ___ different gametes
A
2^23
21
Q
The major contribution of sexual reproduction to evolution has been
A
to provide a process that creates greater genetic variation.
22
Q
Prophase 1
A
Homologous chromosomes pair up, exchange genetic material (Crossing Over) and condense.
23
Q
Metaphase 1
A
Homologous chromosome pairs align at the plate.
24
Q
Anaphase 1
A
Homologous separate and move to opposite poles.
25
Telophase I & Cytokinesis
Two haploid cells form, each with duplicated chromosomes.
26
Prophase II
Chromosomes condense again in both haploid cells.
27
Metaphase II
Chromosomes align at the metaphase plate.
28
Anaphase II
Sister chromatids separate and move to opposite poles.
29
Telophase II and Cytokinesis
Four genetically unique haploid cells form.
30
Order that it happens
PMATC 1 then PMATC 2
31
What is incomplete dominance?
The heterozygous phenotype is a blend of both alleles.
32
What is codominance?
The alleles share traits within the offspring without blending.
33
What is the expected phenotypic ratio of the offspring between double heterozygous individuals?
9:3:3:1
34
What is a dihybrid cross phenotypic ratio?
9:3:3:1
35
If a fly is heterozygous for 2 genes, how many unique gametes will they make?
2^n where n = number of heterozygous pairs
36
What is the probability of an AABBCC offspring from AaBbCc x AaBbCc?
1/64
37
What is the phenotype of a fly that is homozygous dominant for body color and heterozygous for wing size?
Wild type body and wings
38
What is a 'wild type'?
The most common allele in a population.
39
If a gene has a homozygous dominant lethal genotype, what is the genotype ratio of the offspring?
2:1 (excluding AA, which does not survive)
40
What is genetic linkage mapping?
How frequently genes are inherited together.
41
How do you calculate distance between genes?
1. Find recombinant offspring by calculating possible offspring.
42
How do you determine the phenotype ratio from a Punnett square?
Count offspring with same phenotypes, compare with total.
43
What is Mendel’s Law of Segregation?
Alleles separate during gamete formation and unite randomly at fertilization.
44
What is Mendel’s Law of Independent Assortment?
Each pair of alleles segregates independently during gamete formation.
45
What is the probability of offspring being aa from Aa x Aa?
36895
46
What is the probability of heterozygous Bb from Bb x Bb?
36893
47
How do you calculate the probability of aabbcc from AaBbCc x AaBbCc?
1/64
48
How do you calculate the probability of AABbcc from AaBbCc x AaBbCc?
1/32
49
What type of dominance shows a blended trait?
Incomplete dominance
50
What type of dominance shows both alleles fully expressed?
Codominance
51
What are the genotypes for human blood types?
IA, IB, i
52
What blood type alleles are codominant?
IA and IB
53
What blood type alleles are dominant over i?
IA and IB
54
What is the genotype of someone with type O blood?
ii
55
What is the genotype of someone with AB blood?
IAIB
56
What is the ratio of genotypes from a monohybrid cross (Aa x Aa)?
0.043067129629629664
57
What is the ratio of phenotypes from a monohybrid cross (Aa x Aa)?
0.12569444444444455
58
What is a polygenic trait?
A trait controlled by many genes, like height or skin color.
59
What is a carrier?
An individual who is heterozygous for a recessive disorder.
60
What is a sex-linked trait?
A trait associated with genes found on sex chromosomes.
61
Who is more likely to express an X-linked recessive trait?
Males (because they have only one X chromosome)
62
What is an autosomal recessive disorder?
A disorder expressed only if both alleles are recessive.
63
What is an example of an autosomal recessive disorder?
Cystic fibrosis, Tay-Sachs, albinism.
64
What is an autosomal dominant disorder?
A disorder expressed with just one dominant allele.
65
What is an example of an autosomal dominant disorder?
Huntington's disease, polydactyly.
66
How does environment affect phenotype?
Environmental factors can influence gene expression (e.g., soil pH and flower color).
67
What is the genotype of a male with an X-linked recessive trait?
XʳY
68
What is the genotype of a female carrier of an X-linked recessive trait?
XʳX
69
What is a Punnett square?
A diagram used to predict genotypes of offspring.
70
How many gametes are possible from RrYy?
RY, Ry, rY, ry
71
How do you find recombinant frequency?
Recombinants ÷ Total offspring
72
What does 1% recombination equal?
1 centimorgan (cM) — a unit of map distance
73
What is incomplete dominance?
The heterozygous phenotype is a blend of both alleles.
74
What is codominance?
The alleles share traits within the offspring without blending.
75
What is the expected phenotypic ratio of the offspring between double heterozygous individuals?
9:3:3:1
76
What is a dihybrid cross phenotypic ratio?
9:3:3:1
77
If a fly is heterozygous for 2 genes, how many unique gametes will they make?
2^n where n = number of heterozygous pairs
78
What is the probability of an AABBCC offspring from AaBbCc x AaBbCc?
1/64
79
What is the phenotype of a fly that is homozygous dominant for body color and heterozygous for wing size?
Wild type body and wings
80
What is a 'wild type'?
The most common allele in a population.
81
If a gene has a homozygous dominant lethal genotype, what is the genotype ratio of the offspring?
2:1 (excluding AA, which does not survive)
82
What is genetic linkage mapping?
How frequently genes are inherited together.
83
How do you calculate distance between genes?
1. Find recombinant offspring by calculating possible offspring.
84
How do you determine the phenotype ratio from a Punnett square?
Count offspring with same phenotypes, compare with total.
85
What is Mendel’s Law of Segregation?
Alleles separate during gamete formation and unite randomly at fertilization.
86
What is Mendel’s Law of Independent Assortment?
Each pair of alleles segregates independently during gamete formation.
87
What is the probability of offspring being aa from Aa x Aa?
1/4 or 25%
88
What is the probability of heterozygous Bb from Bb x Bb?
1/2 or 50%
89
How do you calculate the probability of aabbcc from AaBbCc x AaBbCc?
1/64
90
How do you calculate the probability of AABbcc from AaBbCc x AaBbCc?
1/32
91
What type of dominance shows a blended trait?
Incomplete dominance
92
What type of dominance shows both alleles fully expressed?
Codominance
93
What are the genotypes for human blood types?
IA, IB, i
94
What blood type alleles are codominant?
IA and IB
95
What blood type alleles are dominant over i?
IA and IB
96
What is the genotype of someone with type O blood?
ii
97
What is the genotype of someone with AB blood?
IAIB
98
What is the ratio of genotypes from a monohybrid cross (Aa x Aa)?
0.043067129629629664
99
What is the ratio of phenotypes from a monohybrid cross (Aa x Aa)?
0.12569444444444455
100
What is a polygenic trait?
A trait controlled by many genes, like height or skin color.
101
What is a carrier?
An individual who is heterozygous for a recessive disorder.
102
What is a sex-linked trait?
A trait associated with genes found on sex chromosomes.
103
Who is more likely to express an X-linked recessive trait?
Males (because they have only one X chromosome)
104
What is an autosomal recessive disorder?
A disorder expressed only if both alleles are recessive.
105
What is an example of an autosomal recessive disorder?
Cystic fibrosis, Tay-Sachs, albinism.
106
What is an autosomal dominant disorder?
A disorder expressed with just one dominant allele.
107
What is an example of an autosomal dominant disorder?
Huntington's disease, polydactyly.
108
How does environment affect phenotype?
Environmental factors can influence gene expression (e.g., soil pH and flower color).
109
What is the genotype of a male with an X-linked recessive trait?
XʳY
110
What is the genotype of a female carrier of an X-linked recessive trait?
XʳX
111
What is a Punnett square?
A diagram used to predict genotypes of offspring.
112
How many gametes are possible from RrYy?
RY, Ry, rY, ry
113
How do you find recombinant frequency?
Recombinants ÷ Total offspring
114
What does 1% recombination equal?
1 centimorgan (cM) — a unit of map distance
115
What is the Hardy-Weinberg Equilibrium?
A principle stating that allele and genotype frequencies remain constant in a population unless influenced by evolutionary forces.
116
What are the five assumptions of Hardy-Weinberg Equilibrium?
No mutation, no natural selection, no gene flow, no genetic drift, and random mating.
117
What is the Hardy-Weinberg allele equation?
p + q = 1
118
What is the Hardy-Weinberg genotype equation?
p² + 2pq + q² = 1
119
How do you calculate allele frequencies from genotype counts?
Use: (2 × homozygous + 1 × heterozygous) / (2 × total individuals)
120
How do you interpret a chi-squared value in H-W testing?
If χ² < 5.99, population is in equilibrium. If χ² > 5.99, evolution is likely occurring.
121
Why use Hardy-Weinberg in real populations?
To detect when allele frequencies differ from expected, which signals evolutionary forces are at work.
122
What is the PKU example used for in population genetics?
It helps calculate q², q, p, and carrier frequency for a real genetic disorder using Hardy-Weinberg equations.
123
How do you calculate the number of individuals expected for each genotype in H-W?
Multiply each expected frequency (p², 2pq, q²) by the total population size.
124
What is the chi-squared formula used in Hardy-Weinberg analysis?
Used to compare actual vs expected genotypes:
1. O = observed # for each genotype
2. E = expected # (from H-W math)
3. Subtract: O − E
4. Square it: (O − E)²
5. Divide: by E
6. Add all up = χ²
If χ² < 5.99 → population IS in equilibrium
If χ² > 5.99 → NOT in equilibrium (evolution likely)
125
What is the threshold chi-squared value for 2 degrees of freedom in H-W?
5.99 — if your χ² is greater, the population is not in equilibrium.
126
What is the purpose of comparing observed and expected genotype frequencies?
To test if a population is in Hardy-Weinberg equilibrium.
127
What is balancing selection?
A type of natural selection that maintains genetic diversity, such as heterozygote advantage or frequency-dependent selection.
128
What is heterozygote advantage?
When individuals with heterozygous genotypes have higher fitness than either homozygote (e.g., sickle cell and malaria).
129
What is frequency-dependent selection?
When the fitness of a phenotype depends on how common or rare it is in the population.
130
What is the probability of offspring being aa from Aa x Aa?
1/4 or 25%
131
What is the probability of heterozygous Bb from Bb x Bb?
1/2 or 50%
132
What is the chi-squared formula used in Hardy-Weinberg analysis?
Used to compare actual vs expected genotypes:
1. O = observed # for each genotype
2. E = expected # (from H-W math)
3. Subtract: O − E
4. Square it: (O − E)²
5. Divide: by E
6. Add all up = χ²
If χ² < 5.99 → population IS in equilibrium
If χ² > 5.99 → NOT in equilibrium (evolution likely)
133
What does Hardy-Weinberg equilibrium assume?
No mutation, random mating, no gene flow, infinite population size, and no selection.
134
What is the purpose of Hardy-Weinberg equilibrium?
To serve as a null model to detect if evolution is occurring.
135
What is the Hardy-Weinberg equation for allele frequency?
p + q = 1 (p = dominant allele frequency, q = recessive allele frequency)
136
What is the Hardy-Weinberg equation for genotype frequency?
p² + 2pq + q² = 1
137
What does each term mean in p² + 2pq + q² = 1?
p² = homozygous dominant, 2pq = heterozygous, q² = homozygous recessive
138
What is the threshold value for chi-squared in H-W equilibrium?
5.99 is the cutoff value (for 2 degrees of freedom at 0.05). If χ² < 5.99 → in equilibrium.
139
How do you calculate allele frequency (p or q)?
From genotype counts: p = [2(AA) + Aa] / 2(total individuals), q = [2(aa) + Aa] / 2N
140
If PKU affects 1 in 10,000 babies (q² = 0.0001), what is the carrier frequency?
q = 0.01, p = 0.99, carrier = 2pq = 2(0.99)(0.01) = 0.0198 or ~2% of the population
141
Population vs. Community
Population- same species
Community- diff species
142
The biome with the most diversity is
Tropical Rainforest
143
Which biome has a permanent layer of ice?
Tundra
144
What causes seasonal patterns in the northern hemisphere?
The tilt of the earth and annual rotation around the sun
145
Which of the biomes have the richest soil?
Temperate grasslands
Very fertile soil
146
Many biomes have grasses maintained by
Fire
147
T&F Deserts are dry because the suns heat evaporates all the water
False
Dry because little to no precipitation
148
Name the biosphere where you live
Earth
149
What is the biome in Las Cruces?
Desert
150
There are 2.2 mil white winged doves in texas meaning about 7 birds per square mile what is this a measure of?
Density
151
Density
number of individuals per unit area
152
Dispersion
Pattern and the way animals are spaced in a population
153
Distribution
Where you find the individuals
where they are located
154
How might you measure population density of dandelions in this field?
count a subset and estimate the population for the area
155
Bushes are evenly spaced in a habitat in new mexico what is this called
Uniform dispersion
156
Humans are found in all continents in the world, what is this called
Distribution
157
Dispersion types
Uniform- an even pattern dispersion
Clumped- individuals are aggregated
Random- unpredictable spacing
158
The J shaped growth curve where populations grow at a constant factor over time is called
Exponential
159
Which is the formula for the exponential growth curve?
rN
160
What is the formula for the logistic growth curve?
rN(K - N)/K
161
Logistic growth rate is slowed by
Carrying capacity (K)
162
The growth rate (r) is 0.25 the birth rate is 0.65 what is the death rate
0.40
birth rate - growth rate = death rate
163
If multiple populations start with the same initial size, what determines which one grows the fastest under exponential growth conditions?
The population with the highest intrinsic growth rate (r) will grow the fastest
164
whooping cranes. the conservation effort of buying land changes the
change in the carrying capacity K
more room to live and create more animals
165
Competition
If both individuals get harmed
166
When an animal eats a plant this is called
Herbivory
Primary consumer
167
Which of these species is an exoparasite
Head lice
168
Animals may pollinate plants while eating nectar. this is called
Mutualism
169
Most frog lays hundreds of thousands of eggs Very few survive what life strategies
Type 3
170
If a plant has 10,000 kcal of energy how much is left for the snake?
10 kcal
171
What percentage of the energy is lost between the producer and the primary consumer?
0.9
172
Which is an abiotic component of ecology?
The carbon in our local caliche layer
173
How are humans adding more carbon into the earth's atmosphere?
Cutting down trees, Driving cars, etc
174
Which compound contributes the most to global climate change?
Carbon Dioxide (CO2)
175
What causes small jagged changes in CO2 Levels in this figure?
Seasonal activity of plants in temperate biomes
176
Population Density formula
Number of individuals/Area
177
The greatest annual input and least seasonal variation in heat occurs in the
Tropics
178
Most of the world's deserts are located at latitudes where
hot, dry air moving toward the poles descends
179
A group of individuals of a single species that occupy the same general area defines a
Population
180
Assume that there are five alligators per acre in a swamp in northern Florida. This is a measure of the alligator population's
Density
181
The Mexican Wolf can be found in New Mexico and Arizona. The is a description of that species
Distribution
182
When you are looking up a "range map" of a species, you are finding out the _____ of that species.
distribution
183
A survivorship curve is a
graph that plots an individual's likelihood of being alive as a function of age.
184
Type 1 survivorship curve is the result of which of the following life history traits?
parents providing a lot of care for a few offspring
185
A newly mated queen ant establishes an ant nest in an unoccupied patch of suitable habitat where resources are abundant. Assuming that no disasters strike the nest, which of the following types of equation will best describe its population growth?
exponential
186
The maximum number of individuals a habitat can support is called its
Carrying capacity
187
If an ecosystem is above its carrying capacity the population will
decrease
188
preventing whooping cranes from extinction required
captive breeding and reintroduction.
189
In an ecosystem, you would expect to find interspecific competition between
populations of two species that utilize the same resources
190
The prokaryotes that cause tooth decay have a ____ relationship with humans
Parasitic
191
A tree is a ____ in an ecosystem
Producer
192
In a food chain consisting of phytoplankton → zooplankton → fish → fishermen, the fishermen are
Tertiary
193
In a food web, what could be true?
Several species of primary consumers may feed on the same species of producer
194
One simple thing that you can do to help safeguard the environment is to eat a diet consisting only of organisms that are
Producers
195
What is an abiotic factor?
temperature
196
The flow of ______ into ecosystems occurs in one direction only and then is lost,
energy; nutrients
197
The level of ecological organization that incorporates abiotic factors is the
Ecosystem
198
Which does not release CO2?
Photosynthesis
199
What is a Type I survival curve
Few offspring and provide substantial parental care
High survival early and middle life, rapid decline later (e.g., humans)
200
What is a Type II survival curve?
Moderate offspring and care
Constant death rate across lifespan (e.g., birds)
201
What is a Type III survival curve
Many offspring (often hundreds or thousands), little to no parental support
High death rate early, survivors live long lives (e.g., trees, fish)
202
Chaparral
Grows around the Mediterranean
Scrubby
203
Tundra
Cold permafrost
Frozen
204
Desert
Very dry hot or cold
205
Tropical Rainforest
Rainiest and warmest biome
Most diverse biome
206
Temperate Broadleaf Forest
Trees lose leaves in the winter
Key word: Deciduous trees
207
Coniferous Forest or Taiga
Cold forests of evergreen trees and pine
Keyword: Pine
Canada, Alaska, Siberia
208
Temperate grasslands
Grassy fertile soil
Key word: great for farming
209
Savanna
Warm grassland, scattered trees
Animals such as zebras lions and antelopes live there
210
Exponential Growth is
J curve
Ideal conditions- lots of food and space, no predators or disease
Population doubles and grows faster over time
rN
growth rate x Population size
211
Logistic Growth is
S shaped curve
Realistic conditions- limited resources
Pattern- starts looking like exponential then slows down as population gets larger
Levels off at the carrying capacity (K)
rN(K-N/K)
212
Batesian Mimicry
palatable organism looks like a toxic one to scare off predators (ex viceroy butterflies trying to mimic monarch butterflies)
213
Müllerian mimicry
two distasteful organisms look alike to signal their toxicity (ex bees and yellow jackets)
214
What are the three components of population structure?
Distribution, density, and dispersion.
215
What is age structure and how is it measured in ecology?
Age structure is the proportion of individuals at different ages; often measured using life tables and survivorship curves.
216
What is a survivorship curve?
A graph that shows the number or proportion of individuals surviving at each age.
217
What is the definition of ecology?
The study of the interaction of organisms and their environment.
218
What is a trophic level?
A level in the food chain representing an organism’s feeding position (e.g., producer, primary consumer, etc.)
219
Why is only 10% of energy passed to the next trophic level?
Most energy is lost as heat, undigested material, or used in metabolism.
220
Which of the following oxidizes inorganic substances to obtain energy and fix CO2?
C) chemoautotrophs
221
The earliest discovered fossils are of ________ dating back to ________ years ago.
B) prokaryotes . . . 3.5 billion
222
A stromatolite is
B) a distinctive layered structure formed by photosynthetic prokaryotes.
223
Rod-shaped bacteria are called
B) bacilli
224
Prokaryotes that twist through the environment are called
D) spirochetes
225
Bacteria that “fix” nitrogen to a form that plants can use are called
C) Rhizobium
226
Bullseye rash after tick bite suggests what disease?
D) Lyme disease
227
Bacteria that manipulate rollie pollies to become female
E) Wolbachia
228
Bacteria that causes food poisoning
A) Salmonella
229
Which statement about Archaea is true?
A) Genetic prospecting has recently revealed many previously unknown species.
230
How do green algae differ from land plants?
B) Some green algae are unicellular.
231
Which is not a hallmark of plants?
A) unicellular
232
Are conifers more closely related to flowering plants or ferns?
A) flowering plants
233
Are ferns more closely related to flowering plants or conifers?
A) flowering plants
234
What taxa have seeds but not flowers?
B) conifers
235
Was the common ancestor of conifers and flowering plants multicellular?
A) yes
236
Did the common ancestor of mosses and ferns have seeds?
B) no
237
Sponges are best described as
D) filter feeders
238
In Cnidaria, what functions as both mouth and anus?
B) a gastrovascular cavity
239
Most animals alive today are
B) invertebrates
240
Which animal displays radial symmetry?
B) a sea anemone
241
Which of the following do not have true tissues?
E) sponges (Porifera)
242
Key adaptation in annelids for flexibility and movement?
C) segmentation
243
Animals with segmentation, jointed appendages, and exoskeleton belong to
E) Arthropoda
244
Three major body sections in insects
B) head, thorax, and abdomen
245
An organism that flies and has an exoskeleton must be
D) an insect
246
What is characteristic of all vertebrates?
A) a skull and a backbone consisting of vertebrae
247
Craniates are chordates that possess
A) a skull
248
How do lampreys differ from fishes?
C) they lack jaws and paired fins
249
Key derived characters of sharks and rays
D) jaws and paired fins
250
Why are amphibians called 'two lives'?
A) they have aquatic larvae and terrestrial adults
251
Adaptation allowing reptiles to complete life cycles on land
C) an amniotic egg
252
Which organism is a marsupial?
B) kangaroo
253
Which characteristic most helps vertebrates in dry environments?
A) the shelled, amniotic egg
254
What does a phylogenetic tree (cladogram) represent?
A hypothesis of evolutionary relationships among species.
255
What are nodes on a cladogram?
Branch points that represent common ancestors.
256
What do branches on a phylogenetic tree represent?
Evolutionary lineages and transitions (traits).
257
How can you tell which species are more closely related on a cladogram?
They share a more recent common ancestor (closer node).
258
What is the function of Rhizobium in plant roots?
It fixes nitrogen from the atmosphere into a usable form for plants.
259
What are cyanobacteria known for?
They produce oxygen through photosynthesis and changed Earth’s atmosphere.
260
What are protists?
Mostly unicellular eukaryotes that can be autotrophic or heterotrophic.
261
What protist causes malaria?
Plasmodium, a type of alveolate.
262
What protist caused the Irish potato famine?
A water mold (oomycete).
263
What are the four major plant groups?
Bryophytes, seedless vascular, gymnosperms, and angiosperms.
264
Which plants lack vascular tissue?
Bryophytes (e.g., mosses).
265
What are gymnosperms?
Seed-producing plants like conifers that do not produce flowers.
266
What are angiosperms?
Flowering plants that produce seeds enclosed in fruits.
267
What do all plants have in common?
Multicellular, sessile, cell walls, chloroplasts, and photosynthesis.
268
What is a defining trait of sponges (Porifera)?
They lack true tissues and symmetry.
269
What are cnidarians known for?
Stinging cells, radial symmetry, and a gastrovascular cavity.
270
What innovation allows annelids to move more flexibly?
Segmentation.
271
What is the function of the exoskeleton in arthropods?
Provides support, protection, and enables jointed movement.
272
What are the four key traits of chordates?
Notochord, dorsal nerve cord, pharyngeal slits, and post-anal tail.
273
What distinguishes mammals from other chordates?
Hair, mammary glands, and live birth in most.
274
What’s the difference between monotremes, marsupials, and placentals?
Monotremes lay eggs, marsupials have pouches, placentals develop via placenta.
275
If two species share a more recent common ancestor with each other than with a third, what does that mean?
They are more closely related to each other than to the third species.
276
What does it mean when a trait is shared among a group on a phylogenetic tree?
It likely evolved in their most recent common ancestor.
277
Can a phylogenetic tree show exact time of divergence?
Not always — unless it’s a scaled tree, it only shows relative relationships, not timing.
