00_all_sbi3u_20250615122951 Flashcards
(239 cards)
1
Q
Inheritance of acquired characteristics
Who created it? What is it?
A
Created by Jean-Baptiste Lamarck
Individuals could pass on characteristics they had acquired during their lives to their offspring
[Also proposed that all species evolve over time and in response to its environment, becoming better adapted in that environment. Also, changes are passed from generation to generation.]
2
Q
Catastrophism
Who created it? What is it?
A
Created by Georges Cuvier
Global catastrophes (like floods) caused the widespread extinction of species
3
Q
Uniformitarianism
Who created it? What is it?
A
Created by Charles Lyell
Geological changes are slow & gradual, and natural laws/processes have not changed over time
4
Q
Evolution by Natural Selection
Who created it? What is it?
A
Created by Charles Darwin
Process in which species change over time to best adapt to their environments
5
Q
Darwin’s observations
A
- Similar flora (plants) & fauna (animals) on the Galapagos as on mainland South America
- Many distinct species of finches & mockingbirds
- Fossilized species were similar to present-day species. Ex. Glyptodon (armadillo) & megatherium (sloths)
6
Q
Fossil record
A
Historical, chronological record of all-known fossils documenting life on Earth and the evidence of past life
7
Q
Evidence in fossil record
A
- There are fossils of those no longer living
- Shallow layers resemble living species
- No fossils of most living species
- The deeper layers you get, the more simple the fossils are
- Fossils are buried deep within rock formations; also, they are found in unexpected locations. Ex. Sea life fossils found in mountain formations & deserts
8
Q
Biogeography
A
Scientific study of geographic distribution of organisms based on both living species & fossils
9
Q
Homologous features
A
Common origin/structure, but different function
10
Q
Analogous features
A
Common function, but different structure
11
Q
Vestigial features
A
Has homologous structure to another species, but it serves no purpose in this species
12
Q
Natural selection
A
The way in which nature favours the reproductive success of some individuals within a population over others
13
Q
Adaption
A
Characteristic/feature of species that makes it well suited for survival or reproductive success in its environment
14
Q
Directional selection
A
Selection that favours a more extreme variation of a trait
Ex. Longer-billed birds are favoured in long-flower environments
15
Q
Stabilizing selection
A
Selection that favours the average phenotype (favoured by the environment; extreme variations are not favoured)
Ex. Average-length billed birds are favoured
16
Q
Disruptive selection
A
Selection that favours opposite extremes of a trait
Ex. Small & large billed birds favoured where there are small & large flowers, both not well-suited for medium-length billed birds
17
Q
Sexual selection
A
Selection that favours the reproductive success of individuals with certain traits over others
18
Q
Genetic drift
A
Random shifting of genetic makeup of next generation (chance). Can result in an allele becoming very common or disappearing entirely.
19
Q
Genetic bottleneck
A
Dramatic (often temporary) reduction in population size, usually resulting in genetic drift.
- Usually the population is all genetically similar
20
Q
Founder effect
A
Genetic drift that happens when a small number of individuals establish a new population
21
Q
Speciation
A
Formation of new species
22
Q
Species
A
All members of a population that can interbreed under natural conditions
23
Q
Allopatric speciation
A
Formation of new species from geographic separation. These species eventually become less and less genetically related as evolution goes on.
Ex. Pacific wrasse and caribbean wrasse cannot interbreed due to a thin strip of land called the Isthmus of Panama dividing the wrasse species 2 million years ago.
24
Q
Sympatric speciation
A
Formation of new species within the same geographic area. Can occur due to competition for resources or mutations. Disruptive selection can lead to this speciation.
Ex. Hawthorn flies laying eggs on both hawthorns & apples after apple trees were brought over to North America.
25
Reproductive isolating mechanism
Any behavioural/structural/biochemical trait that prevents individuals of different species from reproducing successfully together
26
Prezygotic mechanism
Prevents interspecies mating & fertilization (formation of zygotes)
27
Postzygotic mechanism
Prevents maturation & reproduction in offspring from interspecies reproduction (prevents zygote from becoming a viable & reproducing adult)
28
Behavioural isolation
Pre/Post?
Desc.?
Ex.?
Prezygotic mechanism
Different species use different courtship and other mating cues to find and attract a mate.
Ex. Male frogs of different species have unique calls that attract only females of their own species.
29
Hybrid infertility
Pre/Post?
Desc.?
Ex.?
Postzygotic mechanism
Hybrid offspring remain healthy and viable, but are sterile.
Ex. Mules are the sterile hybrid offspring of a horse-donkey cross.
30
Mechanical isolation
Pre/Post?
Desc.?
Ex.?
Prezygotic mechanism
Differences in morphological features may make two species incompatible.
Male damselflies transfer sperm during an unusual mating flight. The male and female genitalia of each species are uniquely shaped and are physically incompatible with other species.
31
Zygotic mortality
Pre/Post?
Desc.?
Ex.?
Postzygotic mechanism
Mating & fertilization are possible, but genetic differences result in a zygote that is unable to develop properly.
Some species of the sheep and goat are able to mate, but the zygote is not viable.
32
Temporal isolation
Pre/Post?
Desc.?
Ex.?
Prezygotic mechanism
Different species breed at different times of the year.
Pussy willow produce flowers in the early spring. They are reproductively isolated from plant species that produce flowers at a different time of the year.
33
Hybrid inviability
Pre/Post?
Desc.?
Ex.?
Postzygotic mechanism
A hybrid individual develops but either dies before birth or, if born alive, cannot survive to maturity.
When tigers and leopards are crossed, the zygote begins to develop but the pregnancy ends in a miscarriage or stillborn offspring.
34
Ecological isolation
Pre/Post?
Desc.?
Ex.?
Prezygotic mechanism
Very similar species may occupy different habitats within a region.
The mountain bluebird lives at high elevations, while the eastern bluebird prefers lower elevations and does not encounter the mountain species.
35
Gametic isolation
Pre/Post?
Desc.?
Ex.?
Prezygotic mechanism
Male gametes may not be able to recognize and fertilize an egg of a different species.
Many marine animals including corals, clams, and sea cucumbers release their sperm and eggs into open water. The sperm recognizes eggs of their own species through chemical markers on the surface of the eggs.
36
Adaptive radiation
When a single species rapidly evolves into many different species, filling formerly empty ecological niches. Ex. Finches
37
Divergent evolution
Large-scale evolution of a group of organisms into many different species, filling specialized ecological niches. Ex. Rodents in Ontario; deer mouse, flying squirrel, beaver
38
Convergent evolution
Evolution of similar traits in distantly related species (analogous features). Ex. Cacti in South America & Africa
39
Co-evolution
Process where one species evolves in response to the evolution of another species. Ex. Hawkmoth & star orchid
40
What is the name of the theory that states that geological changes are slow and gradual and that natural laws and processes have not changed over time? Which scientist is associated with this theory?
Uniformitarianism; Charles Lyell
41
What is the name of the theory that states that the pattern of fossils could be accounted for by a series of global disasters that wiped out most species on Earth? Which scientist is associated with this theory?
Catastrophism; Georges Cuvier
42
Which part of Jean-Baptiste Lamarck's theory does not fit with Charles Darwin's theory of evolution by natural selection?
Jean-Baptiste Lamarck proposed that characteristics acquired during an individual organism's lifetime are passed on to their offspring. (Charles Darwin proposed that the characteristics are already present due to natural variations; if they are adaptive, they will be passed on in greater proportion to the next generation)
43
During his trip on the HMS Beagle, what observations did Charles Darwin make with regard to biogeography?
Charles Darwin observed that fossil species that were similar to living species had the same geographical pattern of distribution (biogeography), suggesting that the living species had evolved from these fossil species.
44
Name 2 unique species found on the Galapagos islands & describe what is unique about each of them
Marine iguana - No other aquatic iguana species in the world
Flightless cormorant - No other species of cormorant that does not fly
45
The forelimbs of the human, horse, cat, bat, and whale have very similar bone structure, but they are adapted to carry out very different functions. This is an example of a _____ feature. What inference can be made about these organisms?
Homologous; can infer that they have common evolutionary origin (ex. a common ancestor)
46
The extra toes on pigs' feet that do not touch the ground are examples of ______ features. What inference can be made about the existence of these features?
Vestigial; can infer that the pigs descended from an ancestral species where the toes were used
47
The wings of birds & the wings of butterflies are both broad, thin, light, and well adapted to their function of flight. They are examples of ____ features. What inference can be made about the mechanism of evolution of these kinds of features?
Analogous; can infer that a similar function (or environment) can lead to similar characteristics developing in organisms that are distantly related
48
Cheetahs have very little genetic diversity because their population was reduced to just 7 individuals 10000 years ago. This is an example of the _______ effect.
bottleneck effect
49
The human population of Iceland was started with a relatively small initial population (primarily of
Norwegian, Scottish, and Irish origin) more than 1000 years ago. This is an example of the
___________________ effect.
founder effect
50
Over many generations, a population of hummingbirds gradually has longer and longer bills (beaks). This is an example of ___________________ selection.
directional
51
Over many generations, a population of hummingbirds has an even greater percentage of individuals with bills of an average length. This is an example of ___________________ selection.
stabilizing
52
Over many generations, a population of hummingbirds gradually has longer and longer bills, that allow them to feed on certain flowers that have extremely long nectar tubes. This is an example of what pattern of evolution?
coevolution
53
What are the 2 most common forms of sexual selection?
female mate selection (females choosing males to mate with) & male-versus-male competition (males competing with each other for territory & access to females for mating).
54
If a population evolves into separate species while within the same geographic area, it is called
___________________ speciation.
sympatric
55
The evolution of a single species into many new species, filling a variety of formerly empty ecological niches is called ___________________ or ___________________.
adaptive radiation or divergent evolution
56
The similar body shapes of sharks and dolphins (even though they are not closely related) is an example of ___________________ evolution.
convergent
57
Male frogs of different species have unique calls that attract only females of their own species.
This is an example of ___________________ isolation, which is a ___________________
reproductive isolating mechanism.
behavioural; prezygotic
58
Zebroids, the hybrid offspring of matings between horses and zebras, cannot reproduce.
This is an example of ___________________ which is a ___________________
reproductive isolating mechanism.
hybrid sterility; postzygotic
59
60
Question
Answer
61
Cotyledons
Structures that supply nutrients to the plant embryo
"Seed leaf"
62
SEEDS
Monocots vs. Eudicots
Monocots - Has 1 cotyledon (seed leaf)
Eudicots - Has 2 cotyledons (seed leaf)
63
Venation
Veins
64
LEAVES
Monocots vs. Eudicots
Monocots - Parallel venation
Eudicots - Branching network venation
65
Vascular bundles
Arrangement of xylem & phloem vascular tissues
Note: Xylem cells are dead at maturity, but phloem cells are alive. Also, xylem & phloem tissues DON'T have nuclei
66
STEMS
Monocots vs. Eudicots
Monocots - Vascular bundles found throughout ground tissue
Eudicots - Vascular bundles form ring
67
Vascular cylinder
Central core of the stem & root of a plant; Contains xylem & phloem tissue
68
ROOTS
Monocots vs. Eudicots
Monocots - Circular
Eudicots - X-shaped
69
Asexual reproduction in plants
Uses stems, leaves, & roots
Grows through mitosis; genetically identical
Ex. Potatoes, strawberries, bryophyllum plants, & dandelions (roots)
70
Sexual reproduction in gymnosperms & angiosperms
Gymnosperms - uses cones; microspore (male) & megaspore (female) are formed
Angiosperms - uses flowers (see other flashcard for info)
71
Self-pollination vs. Cross-pollination
Self-pollination - Pollen goes from one flower to the same flower or another flower on the same plant
Cross-pollination - Pollen goes from one plant to another (same species)
72
Among the 4 main groups of plants, what is the distinguishing feature of bryophytes?
Bryophytes are the only group of plants that are non-vascular.
73
Among the 4 main groups of plants, what is the distinguishing feature of angiosperms?
Angiosperms are the only group of plants that produce flowers and fruit.
74
What is the difference between a monocot and eudicot seed?
Monocot seeds have 1 cotyledon (seed leaf) & Eudicot seeds have 2 cotyledons.
75
Give one example of asexual reproduction in plants that occurs naturally.
Many examples including: specialized stems (strawberry runners, potatoes, spider plants); roots (dandelions); leaves (Bryophyllum); etc.
76
Give one example of asexual reproduction in plants that only occurs with human assistance.
Many examples including: leaf/stem cuttings; tissue culture; grafting; etc.
77
What 3 structures are contained in all seeds?
all seeds contain: seed coat, source of nutrition (endosperm), embryo
78
79
Question
Answer
80
Taxa (singular is taxon)
Categories to classify organisms
81
7 taxas
Kingdom, phylum, class, order, family, genus, species
Most inclusive to most specific
82
Phylogeny
Study of evolutionary relatedness between, and among, species
83
Phylogenetic tree
Diagram depicting the evolutionary relationships between different species or group
84
Clade
A taxonomic group that includes a single common ancestor and all of its descendants
*Protista is the only kingdom that does not represent a clade
85
Domain
highest taxonomic level
86
3 domains (and what kingdoms do they have in them, cell type, and number of cells)
Eubacteria - has kingdom eubacteria - prokaryrote - unicellular
Archaea - has kingdom archaea - prokaryote - unicellular
Eukaryotes - has kingdoms protista, animals, plants, & fungi - eukaryote - multicellular
*protists and fungi are both multicellular and unicellular
87
Cladograms
are used to illustrate the evolutionary relationships, or phylogeny, of different groups of species or organisms
88
Bacteriophage
Virus that infects bacteria by injecting their DNA into the bacterium
89
Lysis
Rupturing of a host cell, releasing about 100 to 200 new viruses into its surroundings
90
Lysogeny
State of dormancy where viral DNA stays in the host's cell for many cycle generations
91
Characteristics of Prokaryotes
Single-celled & lack membrane-bound organelles
92
Characteristics of Eubacteria - Structure
- Has a single loop of DNA, called a Plasmid: Small loop of DNA carrying a small amount of genes.
- Complex cell walls made of peptidoglycan
- Small, hair-like pili
- Some are also covered by a Capsule: Outer layer, provides some protection
93
Characteristics of Eubacteria - Shape & Metabolism
Shape: Spirillum (spiral shape), bacillus (oval shape), or coccus (circle/sphere shape)
Metabolism:
1. Obligate aerobes - cannot survive WITHOUT oxygen.
2. Facultative aerobes - can survive with or without oxygen
3. Obligate anaerobes - cannot survive WITH oxygen
94
Characteristics of Eubacteria - Reproduction & genetic variation as well as endospore
Reproduction: Normally done asexually through...
Binary fission - division of one parent cell into 2 identical daughter cells
Also can happen through...
Conjugation - two cells joining together to exchange genetic information. One bacterial cell passes a copy of Plasmid to a nearby cell through a hollow pilus
Transformation - Bacterial cell takes in genetic information from its environment (from where the cells died).
Eubacteria can form...
Endospore: Highly resistant structure that forms around chromosome when the cell is under stress
95
Protists characteristics
** Not animals, plants, or fungi
Metabolism - aerobic or anaerobic - photoautotrophs (use photosynthesis for food) & heterotrophic (eats animals and plants for food)
Most are unicellular, but some are multicellular
96
Alternation of generations
Alternates between diploid sporophyte (sexual reproduction) & haploid gametophyte (asexual reproduction). Ex. brown algae
97
Characteristics of fungi
- Almost all multicellular
- Source of energy - heterotrophic, external digestion
- Reproduces above ground by fragmentation, budding, or producing spores
- Body is usually below ground; has branched network (mycelium) with hyphae inside it.
- Has cell walls with chitin
98
Main differences of fungi from plants
Not photosynthetic, different cell structure/reproduction methods
99
Characteristics of eukaryotes
Multicellular, has membrane-bound organelles
100
Characteristics of plants
- Multicellular eukaryotes
- Photosynthetic
- Cell walls composed of cellulose
- Terrestrial plants are sessile (stationary)
101
Bryophytes (mosses)
- No vascular system (moves by diffusion, from cell to cell)
- No true leaves/roots/seeds
- Not very tall and can only live in wet conditions
102
Lycophytes (club mosses) & pterophytes (ferns & relatives)
- Vascular tissue (xylem & phloem) which contains lignin
103
Gymnosperms
Produces seeds in cones. Pollen, grains fertilize ovules, producing seeds.
104
Angiosperms
- More than 90% of plants are angiosperms (flowering plants)
- Pollen and ovules found in flowers, seeds are formed in fruits
- 2 major groups - monocots & eudicots
105
Structures in leaves that are adaptations to terrestrial environments
Cuticle and stomata/guard cells (to prevent water loss)
106
Characteristics of animals
Multicellular eukaryotes, heterotrophic, uses aerobic cellular respiration, most are motile (moves), most complex of all organisms
107
What are the 7 taxa in order?
Kingdom, phylum, class, order, family, genus, species
108
What are the 3 domains?
Eubacteria, Archaea, Eukaryotes
109
What types of relationships does a phylogenetic tree show?
Evolutionary relationships (between species or groups)
110
What are 3 characteristics of all prokaryotes?
Here are some examples ...
Single-celled (unicellular), no membrane-bound organelles, single chromosome, reproduce by binary fission, small size
111
Briefly describe how viruses can be used in gene therapy?
Viruses can carry genes to cells to replace, supplement, or repair defective genes
112
What are the 3 shapes of bacteria?
Coccus (spherical), bacillus (rod-shaped), spirillum (spiral)
113
What are 2 processes that are considered sexual reproduction in bacteria?
Conjugation and transformation
114
What is the difference between the cell walls of fungi and of plants?
Fungi cell walls have chitin; plant cell walls have cellulose
115
116
Question
Answer
117
What is genetics?
Scientific study of heredity & variation (of inherited characteristics)
118
Define heredity.
Passing of traits (chromosomes) from parents to offspring
119
What is a gene?
Pieces/portions of DNA that 'codes for a particular trait'
120
What is a locus?
Specific locations for genes
121
What is chromatin?
Tangled strands of DNA & proteins within a eukaryotic nucleus
122
Define chromosome.
Thread-like structures in the nucleus
123
What is an unduplicated chromosome?
Made up of a single DNA molecule & its associated proteins
124
What is a duplicated chromosome?
2 sister chromatids, which are the identical copy of a single chromosome
125
What is mitosis?
Eukaryotic cells’ nucleus is divided equally into 2 new nuclei
126
What is cytokinesis?
A eukaryotic cell divides its cytoplasm into 2 new daughter cells
127
Define sexual reproduction.
Production of offspring through fusion of 2 sex cells; genetically variable
128
What are the advantages of sexual reproduction?
* Variable offspring can be better adapted to new environments
* Some will survive
*Genetic diversity
129
What are the disadvantages of sexual reproduction?
* Must have specialized organs to produce sex cells
* Requires lots of energy
* Biologically costly
* Animals - vulnerable to predators, Plants - producing flowers requires the production of nectar for pollinators
130
What is asexual reproduction?
Production of offspring from a single parent through mitosis & cell division
131
What are the advantages of asexual reproduction?
* Direct & invariable heredity
* No need for mate, special organs, or mating behaviors
132
What are the disadvantages of asexual reproduction?
* Invariable offspring may not adapt to environmental changes
* May become extinct
133
Give examples of asexual reproduction in plants.
* Plants - roots/shoots that develop into new plants (e.g., strawberries, dandelions)
* Budding - New individual develops from outgrowth of body of organism (e.g., hydra, yeast)
* Fragmentation - Parts of fungi break off and grow independently (e.g., mushrooms, starfish)
134
What are the advantages of cloning (asexual reproduction)?
* Mass production of prized animals/plants
* GMOs for insulin production
* Saving endangered species
135
What are the disadvantages of cloning (asexual reproduction)?
* Unethical
* High cost
* Invariable offspring cannot adapt to changing environments
136
What is a haploid cell?
A cell containing half the usual number of chromosomes
## Footnote
Example: Sex (stem) cells
137
What is a diploid cell?
A cell containing 2 copies of each chromosome
138
What is meiosis?
A 2 stage cell division in which resulting daughter cells have half the number of chromosomes as the parent cell; forms gametes (sex cells)
139
How many daughter cells does meiosis produce?
4 non-identical haploid daughter cells (gametes)
140
What occurs during interphase I?
Growth & DNA replication
141
What happens during prophase I of meiosis?
Chromosomes shorten & thicken, exchange genetic information, and are now 2 sister chromatids.
These chromosomes come together in homologous pairs, called tetrads, and is a process called synapsis. Crossing over (mixing of non-sister chromatids of a homologous pair) occurs.
142
What is a tetrad?
A pair of homologous chromosomes, each chromosome has 2 sister chromatids, so in total 4 chromatids
143
What is synapsis?
Physical pairing of homologous chromosomes during prophase I of meiosis
144
What occurs during metaphase I?
Tetrads move to the centre of the cell, aligning their centromeres across the middle of the cell.
145
What happens during anaphase I?
Homologous chromosomes move to opposite poles of the cell. Reduction division occurred, where only 1 chromosome from each homologous pair will be found in each new daughter cell.
146
What is telophase I?
Nuclear membranes begin to form around chromosomes at each end of the cell, and the cell divides, becoming 2 haploid cells
147
What is spermatogenesis?
Production of sperm cells
148
What is oogenesis?
Production of egg cells
149
Is there interphase II?
NO
150
What happens during prophase II?
Nuclear membrane dissolves and spindle fibers begin to form.
151
What happens during metaphase II?
Chromosomes arrange across the middle of the cell, each with 2 sister chromatids attached at the centromere.
152
What happens during anaphase II?
Sister chromatids separate and move to opposite poles of the cell.
153
What happens during telophase II?
Nuclear membrane forms around the chromatids, now called chromosomes.
154
Mitosis vs. Meiosis
Mitosis: Single division, identical daughter cells, 46 chromosomes in end, diploid daughter cells, makes new body cells
Meiosis: 2 divisions, non-identical daughter cells, 23 chromosomes in end, haploid daughter cells, makes gamete (sex cells, sperm & egg) cells
155
Homologous chromosomes
similar in shape, size, & genetic information. Humans have 23 homologous chromosomes in our body cells (22 pairs of autosomes & 1 pair of sex chromosomes). They separate during Anaphase I.
156
What is a karyotype?
A karyotype is the complete set of chromosomes in an organism.
157
What is non-disjunction?
The failure of homologous chromosomes to move to opposite poles of the cell during meiosis
## Footnote
This results in an abnormal number of chromosomes in the daughter cells, specifically gametes with 24 or 22 chromosomes in humans.
158
What are the consequences of non-disjunction?
One daughter cell has an extra chromosome while the other is missing a chromosome
## Footnote
These cells cannot function normally.
159
What is trisomy?
3 homologous chromosomes in place of a homologous pair
## Footnote
Occurs when a gamete with 24 chromosomes joins with a normal gamete (23).
160
What is monosomy?
Single chromosome in place of a homologous pair
## Footnote
Happens when a gamete with 22 chromosomes joins with a normal gamete.
161
What is Down syndrome?
An extra chromosome 21
## Footnote
Characteristics include a round, full face; short height; large forehead.
162
What is Turner Syndrome?
Turner syndrome is characterized by one X and no Y sex chromosome.
163
What are the characteristics of Turner syndrome?
Female in appearance, do not mature sexually, most miscarried before 20th week of pregnancy
164
What is Klinefelter syndrome?
2 X and one Y sex chromosome
## Footnote
Males are usually sterile and exhibit some feminine body characteristics.
165
What is prenatal testing?
Testing for a genetic disorder that occurs prior to birth
## Footnote
This includes methods such as amniocentesis.
166
What is amniocentesis?
A procedure using a long syringe and ultrasound to obtain cells from the fluid-filled sac surrounding the fetus
## Footnote
This is done when the fetus is large enough.
167
What are autosomes?
All chromosome pairs except for sex chromosomes
## Footnote
In humans, there are 22 pairs of autosomes.
168
What are sex cells?
Chromosome 23
## Footnote
They determine the sex of the offspring.
169
What are the 2 strands of a double-stranded chromosome called?
sister chromatids
170
Describe what happens during Anaphase I of meiosis.
spindle fibres contract, separating homologous pairs of chromosomes
171
Describe what happens during Metaphase of mitosis.
spindle fibres pull chromosomes into a single line along the equatorial plate
172
Is Metaphase of mitosis more similar to Metaphase 1 or Metaphase 2 of meiosis? Explain.
Metaphase of mitosis is more similar to Metaphase 2 of meiosis. In both, chromosomes line up in a single line along the equatorial plate.
173
What are 2 purposes for cells in an organism to undergo mitosis?
* growth
* repair (replacement of damaged or dead cells)
174
Define and contrast diploid and haploid.
* diploid describes a cell with 2 sets (or the full set) of chromosomes
* haploid describes a cell with 1 set (or half of the full set) of chromosomes
175
What is the only type of cell that could not be used for cloning an individual organism?
a gamete because it doesn't contain the full set of an organism's chromosomes
176
Name the only type of cell that undergoes meiosis in a human male.
spermatocytes (in the testes of the human male)
177
What is synapsis and when does it occur during meiosis?
Synapsis is the pairing of homologous chromosomes. It occurs during Prophase 1 of meiosis.
178
What is crossing over and when does it occur during meiosis?
Crossing over is the exchange of genetic material between 2 homologous chromosomes. It occurs during Prophase 1 of meiosis (and possibly during early Metaphase 1).
179
If an oocyte undergoes meiosis, what does it produce? (Be specific about the number and type of cells it produces)
Meiosis of an oocyte will produce 3 nuclei (polar bodies) and 1 immature egg cell (ootid)
180
A cat has 38 chromosomes in its muscle cells. How many chromosomes does it have in its heart cells?
38 (muscle cells and heart cells are both diploid)
181
What do '2n' and 'n' refer to?
* '2n' refers to the diploid number
* 'n' refers to the haploid number
182
What is a karyotype?
A karyotype is a picture of a cell's chromosomes.
183
How many autosomes are there in a normal human sperm cell?
There are 22 autosomes (and 1 sex chromosome) in a normal human sperm or egg cell.
184
What is nondisjunction?
Nondisjunction is when homologous pairs do not split during Anaphase 1 of meiosis.
185
Name a nondisjunction disorder, and describe its karyotype.
* Down syndrome (trisomy 21)
* Klinefelter's syndrome (trisomy 23, XXY)
* Turner syndrome (monosomy 23, XO)
* Trisomy 13 (trisomy 13)
186
Explain how a trisomic female (XXX) would be produced.
Nondisjunction would have caused the egg cell to have 2 X chromosomes. When it was fertilized by a normal sperm cell, there would be 3 X chromosomes in the zygote.
187
What are 2 events that occur during interphase?
cell growth, repair, normal cell functions, DNA replication
188
What is amniocentesis and what is it used for?
Amniocentesis is the extraction of a sample of the amniotic fluid of an unborn fetus. It can be used to screen for genetic disorders such as Down Syndrome in a fetus.
189
True-breeding
An organism that produces offspring that are genetically identical for 1 or more traits when self-pollinated or when crossed with another true-breeding organism for the same traits.
## Footnote
Example: True-breeding purple flowers that are self-pollinated or crossed with another true-breeding with purple flowers will produce all offspring with purple flowers.
190
P-generation
Parent plants used in a cross
## Footnote
Cross is a breeding of 2 organisms with different traits
191
F1-generation
Offspring of a P-generation cross.
## Footnote
Also called the filial generation. They are monohybrids (differs in 1 characteristic only), so only studies inheritance in 1 trait
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F2-generation
Offspring of an F1-generation cross
## Footnote
Studies inheritance of both traits.
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Monohybrid cross
Cross designed to study inheritance of only 1 trait
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Law of segregation
Scientific law, where:
1. Organisms inherit 2 copies of genes; one from each parent
2. Parent organisms donate only one copy of each gene in their gametes (sex cells) because the genes separate during meiosis
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Allele
A form of a gene. There are at least 2 alleles for each gene (genes come in pairs on the chromosome), where some are dominant and some are recessive. They're inherited from your parents.
## Footnote
Note: A gene is a piece of DNA that codes for a particular trait.
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Homozygous
An individual that carries 2 of the same alleles for a characteristic.
## Footnote
Example: Both flower colour alleles coded for purple
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Heterozygous
An individual that carries 2 different alleles for a gene
## Footnote
Example: One flower colour coded for purple, while the other one coded for white
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Genotype
Genetic makeup/set of alleles of an individual. All forms of genes, including hidden ones.
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Phenotype
Traits of an individual (appearance). Only expressed alleles (no hidden ones).
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Dominant allele
Allele that is always expressed, if present.
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Recessive allele
Allele expressed only if not in presence of dominant allele
## Footnote
Basically... If the individual is homozygous for the recessive allele
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Test cross
Cross used to see if an individual exhibiting a dominant trait is homozygous or heterozygous for that trait. Done with unknown genotype and homozygous recessive genotype.
## Footnote
If all offspring show dominant phenotype: Homozyous dominant
Both dominant and recessive phenotypes: Heterozygous
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Punnett square
Diagram showing all possible combinations for each allele
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Complete dominance
Only one allele is present, despite the presence of the other allele
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Incomplete dominance
Where neither allele dominates the other and both have an influence on the individual; results in partial expression of both traits. *Genotype still 1:2:1. Only affects phenotype
## Footnote
Example: Snapdragons. Red snapdragon and white snapdragon makes a pink snapdragon
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Co-dominance
Both alleles are expressed fully to produce offspring with a third (mixed) phenotype. *Genotype still 1:2:1. Only affects phenotype
## Footnote
Examples: Shorthorn cattle (red bull and white cow makes roan (red-and-white) cow)
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Multiple alleles
Traits controlled by a single gene with more than 2 alleles.
## Footnote
Example: ABO blood type
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Pedigree
Chart that traces inheritance of a certain trait among members of a family
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Autosomal inheritance
Inheritance of alleles located on autosomal (non-sex) chromosomes
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Sex-linked
Describes an allele that is found on one of the sex chromosomes (x or y) and, when passed on to offspring, is expressed
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X-linked
Phenotypic expression of an allele that is found on the x chromosome (alleles that cause genetic disorders that are only found on the x-chromosome)
## Footnote
Y-linked is the same definition as x-linked but is for y
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Dihybrid cross
A cross that involves 2 genes, each consisting of heterozygous alleles
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Law of independent assortment
If genes are located on separate chromosomes, they will be inherited independently of one another
The F2 generation typically has a phenotype ratio of 9:3:3:1
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What is another term to describe the genotype of a "purebred" organism?
homozygous
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What is the term used to describe the genotype of an organism that contains 2 different alleles?
heterozygous
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What is the term that refers to the observable traits of an organism?
phenotype
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What is the term that refers to the alleles that an individual carries?
genotype
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List any 2 of the traits of pea plants that Mendel studied?
Any 2 of: seed shape, seed colour, pod shape, pod colour, flower colour, flower position,
stem length
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In the following Punnett square, what are the genotype ratios of the F1 generation?
T=tall plant t=short plant
T T
t Tt Tt
t Tt Tt
100% heterozygous (100% Tt)
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In the following Punnett square, what are the phenotype ratios of the F1 generation?
B=brown eyes b=blue eyes B b
B BB Bb
b Bb bb
75% brown eyes, 25% blue eyes
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What is the purpose of a test cross?
to determine the genotype of an individual showing the dominant phenotype
(the homozygous dominant genotype or the heterozygous genotype)
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What does a circle represent in a pedigree chart?
a female
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If a circle/square is coloured on a pedigree chart, what does that indicate?
It indicates that that individual expresses that trait.
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If a circle/square is half shaded on a pedigree chart, what does that indicate?
It indicates that the individual is heterozygous for the recessive trait (a carrier)
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In fruit flies, there are 4 alleles for eye colour, and the dominance hierarchy is:
red > apricot > honey > white. In a female fruit fly, how many possible genotypes
are there for red eye colour?
4 (homozygous, and then heterozygous with each of the other alleles)
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In certain types of cows, there are 2 alleles for hair colour: red and white. When a cow
has the heterozygous genotype, its phenotype is roan (red hairs and white hairs present).
What is this an example of?
codominance
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Give an example of codominance in human blood type alleles.
AB blood. A (I A) and B (I B) alleles are codominant
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When a snapdragon flower is heterozygous and contains both the red allele and the white
allele, its phenotype is a pink flower. This is an example of...
incomplete dominance
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If genes are on located on separate chromosomes, they are inherited independently of
each other. This is called the law of ...
independent assortment
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In guinea pigs, black coat colour (B) is dominant over white (b), and short hair lenth (H) is
dominant over long (h). What is the genotype of a guinea pig that is homozygous for black
and heterozygous for short hair?
BBHh
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If a trait is sex-linked, how many possible genotypes are there for this trait in a male?
2
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If a trait is sex-linked, how many possible genotypes are there for this trait in a female?
3
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What blood type is the "universal donor" (i.e. it will be accepted by people of any blood
type)?
Which is the "universal acceptor" (can accept any type of blood)?
1. type O (more specifically type O negative) [O negative blood donors are universal because there's nothing in their blood for a patient's antibodies to 'attack'.]
2. type AB (specifically type AB positive) [People with type AB+ blood are universal recipients because they have no antibodies to A, B or Rh in their blood and can receive red blood cells from a donor of any blood type.]
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Red-green colourblindness is caused by a recessive sex-linked allele. If you have a mother with normal vision and a father who is colourblind, is it possible for them to have a daughter who is colourblind?
only if the mother is heterozygous for (or a carrier of) colourblindness
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What is point mutation?
A small change in nitrogenous base sequence of a DNA (a single-base pair)
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Types of point mutations?
1. Base-pair substitution: ACA > AGA
2. Insertion: ACA > ATCA
3. Deletion: ACA > AA
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What is chromosome mutation?
Error that involves the entire chromosome or a large part of a chromosome (ex. nondisjunction which is the failure of homologous chromosomes or sister chromatids to separate properly during cell division)
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What is spontaneous mutation?
Occurs randomly, by accident.
## Footnote
Ex. Errors in cell division
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What is induced mutation?
Occurs because of exposure to outside factors (environmental)
## Footnote
Ex. UV radiation
