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Questions and Answers
What is the primary result of natural selection according to Darwin's inferences?
What is the primary result of natural selection according to Darwin's inferences?
All offspring produced through asexual reproduction are genetically identical to the parent.
All offspring produced through asexual reproduction are genetically identical to the parent.
True
What process occurs during binary fission in eukaryotic cells?
What process occurs during binary fission in eukaryotic cells?
Mitosis
The process by which amoebae can produce multiple offspring is called ______.
The process by which amoebae can produce multiple offspring is called ______.
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Match the following reproduction types with their descriptions:
Match the following reproduction types with their descriptions:
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Which of the following statements is true regarding offspring in sexual reproduction?
Which of the following statements is true regarding offspring in sexual reproduction?
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In multicellular eukaryotes, simple splitting can occur to reproduce asexually.
In multicellular eukaryotes, simple splitting can occur to reproduce asexually.
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What is the primary reason individuals produce more offspring than needed to replace themselves?
What is the primary reason individuals produce more offspring than needed to replace themselves?
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What is a characteristic of Y-linked traits?
What is a characteristic of Y-linked traits?
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X-linked traits affect males and females equally.
X-linked traits affect males and females equally.
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What kind of mutations involve the insertion of an extra base into a DNA sequence?
What kind of mutations involve the insertion of an extra base into a DNA sequence?
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Red-green color blindness is a recessive X-linked trait often caused by the mutation of the allele X^r^. The phenotype affected is characterized by __________.
Red-green color blindness is a recessive X-linked trait often caused by the mutation of the allele X^r^. The phenotype affected is characterized by __________.
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Match the types of mutations with their descriptions:
Match the types of mutations with their descriptions:
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Which of the following best describes mutations?
Which of the following best describes mutations?
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The theory of evolution suggests that all species share a common ancestor.
The theory of evolution suggests that all species share a common ancestor.
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What factor is most likely to influence phenotype variation within a population?
What factor is most likely to influence phenotype variation within a population?
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The natural selection of genetic changes leads to phenotypes best suited to the __________.
The natural selection of genetic changes leads to phenotypes best suited to the __________.
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What does complete dominance mean in genetic inheritance?
What does complete dominance mean in genetic inheritance?
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What determines the value of a feature as an adaptation?
What determines the value of a feature as an adaptation?
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Freshwater fish gills are always adaptive regardless of environmental conditions.
Freshwater fish gills are always adaptive regardless of environmental conditions.
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What happens when an organism approaches its tolerance limits?
What happens when an organism approaches its tolerance limits?
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The ______ range identifies variations in environmental conditions for a particular species.
The ______ range identifies variations in environmental conditions for a particular species.
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Match the following adaptations with their examples:
Match the following adaptations with their examples:
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Which abiotic factor is NOT mentioned as part of the environmental conditions in a habitat?
Which abiotic factor is NOT mentioned as part of the environmental conditions in a habitat?
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Tolerance ranges are the same for all species.
Tolerance ranges are the same for all species.
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What do organisms need to do if an abiotic factor exceeds their tolerance range?
What do organisms need to do if an abiotic factor exceeds their tolerance range?
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What do some frog species do when their waterholes begin to dry out?
What do some frog species do when their waterholes begin to dry out?
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Frogs come out of dormancy only when temperatures drop significantly.
Frogs come out of dormancy only when temperatures drop significantly.
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What is the term used for the inactive state frogs enter when in dormancy?
What is the term used for the inactive state frogs enter when in dormancy?
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Match the following animal species with their survival strategy:
Match the following animal species with their survival strategy:
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What allows the frogs to survive while buried in mud?
What allows the frogs to survive while buried in mud?
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The Budgerigars only travel during the hottest part of the day.
The Budgerigars only travel during the hottest part of the day.
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How long can frogs remain buried in the mud until they become active again?
How long can frogs remain buried in the mud until they become active again?
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What is one strategy that fish use to increase the chances of fertilisation?
What is one strategy that fish use to increase the chances of fertilisation?
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All terrestrial animals use internal fertilisation.
All terrestrial animals use internal fertilisation.
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What technique do male frogs use to increase the chance of fertilisation?
What technique do male frogs use to increase the chance of fertilisation?
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In sharks, males use ______ to transfer sperm to females.
In sharks, males use ______ to transfer sperm to females.
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Match the following animal groups with their fertilisation methods:
Match the following animal groups with their fertilisation methods:
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What feature do male insects have to assist in fertilisation?
What feature do male insects have to assist in fertilisation?
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Internal fertilisation increases the chances of gametes meeting.
Internal fertilisation increases the chances of gametes meeting.
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In octopi, how does the male transfer sperm to the female?
In octopi, how does the male transfer sperm to the female?
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All terrestrial animals use internal fertilisation except for ______ that mate in the water.
All terrestrial animals use internal fertilisation except for ______ that mate in the water.
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Which statement is true regarding the fertilisation method of reptiles?
Which statement is true regarding the fertilisation method of reptiles?
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Study Notes
Sex-Linked Traits
- Traits carried on the X chromosome are called X-linked traits.
- Traits carried on the Y chromosome are called Y-linked traits.
- Males only have one X chromosome, so they are more likely to express X-linked traits.
- Females have two X chromosomes, so they are less likely to express X-linked traits.
- Only males can express Y-linked traits because females lack the Y chromosome.
- For sex-linked genes, the allele symbols are written as a superscript to an X.
Red Green Color Blindness
- A recessive X-linked trait affecting about 8% of males and 0.5% of females.
- Several types of red-green color blindness exist, with deuteranopia being the most common.
- The alleles for normal vision and deuteranopia are X^R^ and X^r^, respectively.
- Normal vision genotypes:
- X^R^X^R^
- X^R^X^r^
- X^R^Y
- Deuteranopia genotypes:
- X^r^X^r^
- X^r^Y
Mutations
- A change in the DNA base sequence that occurs spontaneously in our cells.
- Mutations happen frequently, particularly during DNA replication.
- Carcinogens and certain types of radiation increase the risk of mutations.
- Most mutations occur in non-coding DNA, which plays an important role in gene expression.
Consequences of Mutations
- Mutations can change the protein's amino acid sequence, leading to a different protein.
- Most mutations have no significant effect, and they often only affect a protein slightly.
Types of Mutations
- Substitutions: One base in a sequence is replaced with another.
- Insertions: An extra base is inserted into the sequence, shifting all subsequent bases.
- Deletions: One base is deleted from a sequence, shifting all subsequent bases to the left.
Variation and Evolution
- Variation refers to different phenotypes within a population.
- Everyone has a unique genome.
- The environment plays a role in phenotype characteristics.
- Variations are mostly due to mutations.
- Individuals with beneficial mutations are more likely to survive, reproduce, and pass on their mutated genes.
Evolution
- The inheritance of certain characteristics within a population over multiple generations can lead to changes in the whole species or even the development of a new species.
- The theory of evolution by natural selection suggests that all living species evolved from simple life forms.
- The natural selection of genetic changes that give rise to phenotypes best suited to the environment drives evolution.
- Over time, populations within a species can become so genetically distinct that they can no longer interbreed, resulting in two new species.
Phenotype Variation
- Phenotype variations occur due to the interaction between genes and the environment.
Modes of Inheritance
-
Complete Dominance: One trait is fully dominant over the other, which is recessive.
- Dominant: An allele encoding a protein that influences the phenotype of a heterozygote.
- Recessive: An allele encoding a protein that does not influence the phenotype of a heterozygote.
Darwin's Observations
- There is phenotypic variation between members of a species.
- Offspring tend to resemble their parents.
- Individuals produce more offspring than needed to replace themselves.
- Not all offspring survive to reach sexual maturity.
Darwin's Inferences
- Individuals with traits that increase their chances of survival and reproduction leave more offspring.
- The unequal chances of reproduction lead to the accumulation of favorable traits in the population over generations.
Asexual Reproduction
- The ability to produce new offspring without needing a mate.
- The offspring are genetically identical to the parent and are known as clones.
Methods of Asexual Reproduction
-
Binary Fission in Prokaryotes:
- Replication of the circular DNA molecule.
- Attachment of DNA molecules to the plasma membrane.
- Cell lengthening.
- Division of the cell into two through a constriction and septum formation.
-
Binary Fission in Eukaryotes:
- Occurs in unicellular eukaryotes, involving mitosis.
-
Multiple Fission:
- Occurs in amoebae, where mitosis occurs repeatedly, forming many nuclei within a single cell.
-
Multicellular Eukaryotes:
- Simple multicellular animals can reproduce asexually by splitting into two.
External Fertilization
- The fusion of gametes (sperm and egg) occurs outside the body of the female.
- Species that use external fertilization have developed strategies to increase the chances of fertilization.
-
Fish:
- Courtship displays increase the chance of fertilization.
-
Frogs:
- Males tightly clasp females during egg release, increasing the chance of sperm release over the eggs.
Internal Fertilization
- Sperm is delivered directly into the female's reproductive tract, and fertilization occurs internally.
-
Marine Animals:
- Sharks: Males use claspers to deliver sperm into the female's vagina.
- Octopi: One of the male's arms is specialized to transfer sperm to the female.
-
Insects:
- Male insects have complex genital structures to transfer sperm packages into the female's reproductive tract.
-
Reptiles:
- The first vertebrates to evolve a male copulatory organ, enabling direct sperm transfer.
Adaptations
- Adaptative features are innate and built into an organism's genetic makeup.
- The value of an adaptation depends on the organism's way of life and environmental conditions.
- Example: Gills are efficient for extracting oxygen from water but are maladaptive in air.
Tolerance Range
- Every habitat has abiotic factors that create environmental conditions.
- The tolerance range identifies the variations in environmental conditions that a species can survive and reproduce in.
- The optimum range is within the tolerance range, while the limits are the extreme values.
- Organisms experience physiological stress when approaching the tolerance limits.
Adaptations to Tolerance Ranges
- Organisms may not survive if abiotic factors fall outside their tolerance range, unless they can:
- Escape from the change.
- Compensate for the change.
- Migration: Moving from affected areas to favorable areas.
- Burrowing: Retreating underground to escape unfavorable conditions.
Tolerance Range Examples
-
Frogs:
- Some species burrow into mud during droughts, entering dormancy.
-
Molluscs:
- Some species seal themselves inside their shells with an operculum.
Survival by Migration
- Some species migrate to areas with favorable conditions during droughts.
- Banded Stilts: Fly to other salt lakes when their original lake dries up.
- Budgerigars: Travel to areas with food and water during cooler periods of the day.
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Description
Explore the fascinating world of sex-linked traits through this quiz. Learn about X-linked and Y-linked traits, with a focus on red-green color blindness and genetic mutations. Test your knowledge and understand how these traits are inherited differently in males and females.
