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Questions and Answers
What is the term for differences in characters among individuals of the same species?
What is the term for differences in characters among individuals of the same species?
All variations produced during reproduction have equal chances of survival.
All variations produced during reproduction have equal chances of survival.
False
What is the branch of biology that studies heredity and variations?
What is the branch of biology that studies heredity and variations?
Genetics
During sexual reproduction, variations can result from __________ during meiosis.
During sexual reproduction, variations can result from __________ during meiosis.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Which of the following does NOT contribute to variations in living organisms?
Which of the following does NOT contribute to variations in living organisms?
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Human beings can inherit characteristics directly as exact copies from their parents.
Human beings can inherit characteristics directly as exact copies from their parents.
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Give an example of a variation found among human beings.
Give an example of a variation found among human beings.
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What is the primary focus of the branch of biology called Genetics?
What is the primary focus of the branch of biology called Genetics?
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Gregory Mendel used corn plants for his experiments on inheritance.
Gregory Mendel used corn plants for his experiments on inheritance.
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What are the terms used to describe individuals with two similar factors for a trait?
What are the terms used to describe individuals with two similar factors for a trait?
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Mendel's first generation of offspring is referred to as the ______.
Mendel's first generation of offspring is referred to as the ______.
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Match the following terms related to Mendel's experiments with their definitions:
Match the following terms related to Mendel's experiments with their definitions:
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How many contrasting traits did Mendel specifically study in pea plants?
How many contrasting traits did Mendel specifically study in pea plants?
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The principle of paired factors states that each characteristic is controlled by a single factor.
The principle of paired factors states that each characteristic is controlled by a single factor.
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What does it mean for an individual to be heterozygous?
What does it mean for an individual to be heterozygous?
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What term is used to describe the trait that expresses itself in the presence of two dissimilar factors?
What term is used to describe the trait that expresses itself in the presence of two dissimilar factors?
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The recessive gene is represented by a capital letter.
The recessive gene is represented by a capital letter.
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What does the Principle of Segregation state?
What does the Principle of Segregation state?
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In a Monohybrid cross, Mendel observed a phenotypic ratio of ____ in the F2 generation.
In a Monohybrid cross, Mendel observed a phenotypic ratio of ____ in the F2 generation.
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What is formed when a male gamete fuses with a female gamete during fertilization?
What is formed when a male gamete fuses with a female gamete during fertilization?
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Which type of cross involves two traits?
Which type of cross involves two traits?
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Humans possess 23 pairs of chromosomes, with all of them involved in sex determination.
Humans possess 23 pairs of chromosomes, with all of them involved in sex determination.
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In a Dihybrid cross, all F1 offspring display both dominant traits.
In a Dihybrid cross, all F1 offspring display both dominant traits.
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How many genes are estimated to be present in human beings?
How many genes are estimated to be present in human beings?
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The chromosomes concerned with sex determination are called ______.
The chromosomes concerned with sex determination are called ______.
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What did Mendel mean by 'factors' in his experiments?
What did Mendel mean by 'factors' in his experiments?
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Which pair of chromosomes represents a male in human beings?
Which pair of chromosomes represents a male in human beings?
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A recessive factor can control the synthesis of a fully functional structural protein or enzyme.
A recessive factor can control the synthesis of a fully functional structural protein or enzyme.
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If a gene for an enzyme is altered to be less efficient, the amount of hormone produced will be ______.
If a gene for an enzyme is altered to be less efficient, the amount of hormone produced will be ______.
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Study Notes
Heredity and Evolution
- Living organisms produce offspring similar to their parents, but not exact copies.
- Variations arise from changes in DNA or sexual reproduction.
- Errors in DNA copying and random fertilization contribute to variation.
- Sexual reproduction results in more variations compared to asexual reproduction.
- Variations are less noticeable in asexually reproduced plants, such as sugarcane.
- Humans have more distinct variations due to sexual reproduction.
- Inheritance is the process where characteristics are passed from one generation to the next.
- Heredity is the inheritance of characteristics from parents to offspring.
- Variations are differences among individuals within a species.
- Genetics is the branch of biology studying heredity and variations.
Accumulation of Variations During Reproduction
- Inheritance provides a common basic body design and slight variations.
- Offspring inherit parental characteristics but are not exact copies.
- Variation exists among individuals of a species in some traits.
- Variations, particularly beneficial ones, are selected by nature.
Earlobes as an Example of Variation
- Earlobes are either free-hanging (free earlobes) or attached to the head (attached earlobes).
- These variations exist in the human population.
Heredity
- Gregor Mendel was the first to systematically study inheritance.
- He experimented with pea plants, focusing on seven contrasting traits.
Mendel's Seven Traits in Pea Plants
- Pea shape (round or wrinkled)
- Pea color (green or yellow)
- Pod shape (constricted or inflated)
- Pod color (green or yellow)
- Flower color (purple or white)
- Plant size (tall or dwarf)
- Position of flowers (axial or terminal)
Genetical Terms
- Trait: A specific characteristic of an organism (e.g., tallness, color).
- Phenotype: The observable traits of an organism.
- Genotype: The genetic makeup of an organism.
- F1 generation: First generation of offspring from a cross.
- F2 generation: Second generation of offspring from a cross.
- Selfing: Crossing of two organisms of the same kind.
- Homozygous: Having two similar factors for a trait (e.g., TT for tall).
- Heterozygous: Having two dissimilar factors for a trait (e.g., Tt for tall).
Principles of Inheritance
- Principle of paired factors: Each trait is controlled by a pair of factors (now called genes).
- Principle of dominance: In heterozygous individuals, one factor (dominant) expresses itself while the other (recessive) does not.
- Principle of segregation: Each gamete receives only one factor of each pair during gamete formation.
- Principle of independent assortment: Factors for different traits segregate independently during gamete formation.
Dihybrid Cross
- A cross involving two traits.
- Mendel's dihybrid crosses showed that traits can be inherited independently.
How Traits are Expressed
- Inheritance of traits occurs through hereditary units (genes).
- Genes are a pair of factors that work in pairs.
- Each parent has a pair of genes for each trait.
Mechanism of Heredity
- Genes are segments of DNA located on chromosomes.
- DNA carries the information for making proteins.
- Dominant genes code for fully functional proteins or enzymes.
- Recessive genes code for partially functional or defective proteins or enzymes.
Sex Determination
- Sex in humans is determined genetically by chromosomes.
- Human cells have 46 chromosomes (23 pairs).
- 22 pairs are autosomes, while one pair (23rd) are sex chromosomes.
- Females have XX chromosomes.
- Males have XY chromosomes.
- The sex of the offspring is determined by the male gamete (sperm).
Sex Determination in Other Animals
- In some animals, the sex is determined by environmental factors, like temperature during incubation.
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Description
Test your knowledge on the concepts of heredity and evolution, including the processes of DNA variations and sexual reproduction. This quiz covers fundamental principles of genetics and how traits are passed from parents to offspring. Understand the significance of variations in living organisms and their impact on evolution.
