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Questions and Answers
What primarily determines the sequence of amino acids in a protein?
What primarily determines the sequence of amino acids in a protein?
- The environmental conditions during translation.
- The availability of tRNA molecules.
- The shape of the ribosome.
- The sequence of bases in a gene. (correct)
Which of the following is an example of discontinuous variation?
Which of the following is an example of discontinuous variation?
- Human height.
- Body mass in dogs.
- Leaf length in trees.
- ABO blood groups. (correct)
In a monohybrid cross, if both parents are heterozygous (Tt), what is the expected phenotypic ratio of the offspring, assuming complete dominance?
In a monohybrid cross, if both parents are heterozygous (Tt), what is the expected phenotypic ratio of the offspring, assuming complete dominance?
- 1:2:1
- 9:3:3:1
- 1:1
- 3:1 (correct)
What is the relationship between a gene and a protein?
What is the relationship between a gene and a protein?
In genetics, what does the term 'homozygous' refer to?
In genetics, what does the term 'homozygous' refer to?
If a plant with the genotype $I^AI^B$ is crossed with a plant with the genotype $I^AI^O$, what are the possible blood group phenotypes of their offspring?
If a plant with the genotype $I^AI^B$ is crossed with a plant with the genotype $I^AI^O$, what are the possible blood group phenotypes of their offspring?
Which statement best describes the role of DNA in controlling cell function?
Which statement best describes the role of DNA in controlling cell function?
A scientist observes a deviation from the expected phenotypic ratio in a genetic cross. What is the most likely explanation for this deviation?
A scientist observes a deviation from the expected phenotypic ratio in a genetic cross. What is the most likely explanation for this deviation?
A mutation in a gene results in a protein with a significantly different shape. How might this altered shape affect the protein's function?
A mutation in a gene results in a protein with a significantly different shape. How might this altered shape affect the protein's function?
Consider a hypothetical scenario where a newly discovered gene has three alleles: $A_1$, $A_2$, and $A_3$. $A_1$ exhibits complete dominance over $A_2$, $A_2$ exhibits complete dominance over $A_3$, and $A_1$ is lethal in the homozygous condition. What is the expected phenotypic ratio in a cross between two individuals with the genotype $A_2A_3$?
Consider a hypothetical scenario where a newly discovered gene has three alleles: $A_1$, $A_2$, and $A_3$. $A_1$ exhibits complete dominance over $A_2$, $A_2$ exhibits complete dominance over $A_3$, and $A_1$ is lethal in the homozygous condition. What is the expected phenotypic ratio in a cross between two individuals with the genotype $A_2A_3$?
Which process leads to the evolution of a species over time?
Which process leads to the evolution of a species over time?
What is the outcome of artificial selection?
What is the outcome of artificial selection?
MRSA (methicillin-resistant Staphylococcus aureus) is an example of what?
MRSA (methicillin-resistant Staphylococcus aureus) is an example of what?
Which of the following is NOT a source of genetic variation within a population?
Which of the following is NOT a source of genetic variation within a population?
Which of the following best describes the role of competition in natural selection?
Which of the following best describes the role of competition in natural selection?
What is the most direct effect of ionizing radiation on genetic material?
What is the most direct effect of ionizing radiation on genetic material?
Which of the following is the most comprehensive definition of evolution?
Which of the following is the most comprehensive definition of evolution?
Considering the steps of artificial selection, how would a breeder MOST likely ensure the perpetuation of a novel, recessive trait that initially appears in only a few offspring?
Considering the steps of artificial selection, how would a breeder MOST likely ensure the perpetuation of a novel, recessive trait that initially appears in only a few offspring?
How does the reduced susceptibility of certain mosquito populations to specific insecticides exemplify natural selection?
How does the reduced susceptibility of certain mosquito populations to specific insecticides exemplify natural selection?
In a scenario where a population of plants is subjected to a rapidly changing climate that favors drought resistance, but also selects against larger seed size due to resource scarcity, what evolutionary trade-off is MOST likely to occur?
In a scenario where a population of plants is subjected to a rapidly changing climate that favors drought resistance, but also selects against larger seed size due to resource scarcity, what evolutionary trade-off is MOST likely to occur?
Flashcards
Chromosome Mutation
Chromosome Mutation
Change in the number or structure of chromosomes.
Down's Syndrome
Down's Syndrome
Having 47 chromosomes instead of the normal 46 due to a chromosome mutation.
Sources of Genetic Variation
Sources of Genetic Variation
Mutation, meiosis, random mating, and random fertilization.
Mutation Rate Increase
Mutation Rate Increase
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Natural Selection
Natural Selection
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Evolution
Evolution
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Antibiotic Resistance
Antibiotic Resistance
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Artificial Selection
Artificial Selection
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Steps of Artificial Selection
Steps of Artificial Selection
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Role of Artificial Selection
Role of Artificial Selection
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Variation
Variation
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Continuous Variation
Continuous Variation
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Discontinuous Variation
Discontinuous Variation
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DNA
DNA
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Gene
Gene
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Inheritance
Inheritance
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Allele
Allele
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Dominant Allele
Dominant Allele
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Phenotype
Phenotype
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Codominance
Codominance
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Study Notes
Variation
- Variation is the differences between individuals of the same species.
Continuous Variation
- Results in a range of phenotypes between two extremes.
- Body length and body mass are examples
- Genes and the environment causes it
Discontinuous Variation
- Results in a limited number of phenotypes with no intermediates.
- ABO blood groups, seed shape, and seed color in peas are examples.
- Genes usually cause it alone
Investigating Variation
- Involves the study and description of both continuous and discontinuous variation.
Structure of DNA
- Two strands are coiled into a double helix.
- Each strand is made of nucleotides.
- Each nucleotide contains a base: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).
- Bases pair up: A with T and C with G.
- Bonds between base pairs hold the strands together.
Gene Definition
- A length of DNA that codes for a protein.
DNA Function
- Controls cell function by controlling protein production including enzymes.
Protein Synthesis
- The sequence of bases in a gene determines the sequence of amino acids in a protein.
- Different amino acid sequences give proteins different shapes.
Inheritance
- Transmission of genetic information from one generation to the next.
Allele
- An alternative form of a gene.
Key Terms
- Dominant: Allele expressed in the phenotype, even if only one copy is present.
- Recessive: Allele only expressed if two copies are present.
- Phenotype: Physical expression of a gene.
- Genotype: Genetic makeup of an organism.
- Homozygous: Two identical alleles for a gene (e.g., TT or tt).
- Heterozygous: Two different alleles for a gene (e.g., Tt).
Genetic Diagrams
- Punnett squares are used to predict monohybrid cross outcomes.
- Phenotypic ratios include 1:1 or 3:1
Observed vs. Expected Ratios
- Differences occur due to small sample sizes (random chance).
Pure-Breeding
- Two identical homozygous individuals breeding together produce pure breeding offspring
Codominance
- Both alleles are expressed equally in the phenotype.
- ABO blood groups (Iᴬ, Iᴮ, Iº) have phenotypes A, B, AB, and O.
Sex Determination
- Humans: XX (female), XY (male).
Gene Mutation
- Random change in the base sequence of DNA.
- Sickle cell anaemia is caused by a mutation in the hemoglobin gene.
Chromosome Mutation
- Change in chromosome number or structure.
- Down's syndrome involves 47 chromosomes instead of 46.
Sources of Genetic Variation
- Mutation, meiosis, random mating, and random fertilisation.
Mutation Rate
- Is increased by ionising radiation and some chemicals.
Natural Selection
- The process by which species evolve over time.
- Variation exists within populations.
- Many offspring are produced.
- Struggle for survival involves competition for resources.
- Better adapted individuals survive and reproduce, passing on their alleles to the next generation.
Evolution
- Inherited features of a population changes over time due to natural selection.
Antibiotic Resistance
- Example: MRSA (methicillin-resistant Staphylococcus aureus).
- Bacteria with resistance survive and reproduce, passing on resistance genes.
Artificial Selection (Selective Breeding)
- Humans select organisms with desirable traits.
- Steps include selecting parents with desirable features, crossing them to produce the next generation, and repeating over many generations with selection of offspring with desirable features.
- Used to produce economically important plants (e.g., high-yield crops) and animals (e.g., livestock with desirable traits).
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Description
Explore variation within species, including continuous and discontinuous types, and the structure and function of DNA. Understand how DNA codes for proteins and controls cell function. Learn about the building blocks of DNA and base pairing rules.
