Biology Chapter 11 Flashcards
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Questions and Answers

What did Gregor Mendel use to study the inheritance of traits?

pea plants

What are offspring that result from crosses between true breeding parents with different traits called?

hybrids

What are the chemical factors that determine traits called?

genes

How are traits inherited according to Gregor Mendel?

<p>through the passing of factors from parents to offspring</p> Signup and view all the answers

When Gregor Mendel crossed a tall plant with a short plant, what did the F1 plants inherit?

<p>an allele for tallness from the tall parent and an allele for shortness from the short plant</p> Signup and view all the answers

What does the principle of dominance state?

<p>some alleles are dominant and others are recessive</p> Signup and view all the answers

Why were all offspring tall when true-breeding tall plants were crossed with true-breeding short plants?

<p>the allele for tall plants is dominant</p> Signup and view all the answers

What happens if the tall F1 pea plants are allowed to self-pollinate?

<p>some of the offspring will be tall, and some will be short</p> Signup and view all the answers

How can the principle of probability be used in genetics?

<p>to predict the traits of the offspring produced by genetic crosses</p> Signup and view all the answers

In the P generation, what is the probability that an F2 plant will be tall when a tall plant is crossed with a short plant?

<p>75%</p> Signup and view all the answers

What do you call organisms that have two identical alleles for a particular trait?

<p>homozygous</p> Signup and view all the answers

What does a Punnett square show?

<p>the possible genetic outcomes of a cross</p> Signup and view all the answers

What is shown by a Punnett square showing Gregor Mendel's cross between true-breeding tall plants and true-breeding short plants?

<p>a genotype that was different from that of both parents</p> Signup and view all the answers

What principle states that during gamete formation, genes for different traits separate without influencing each other's inheritance?

<p>Principle of Independent Assortment</p> Signup and view all the answers

How many different allele combinations would be found in the gametes produced by a pea plant whose genotype was RrYY?

<p>2</p> Signup and view all the answers

If a pea plant that is heterozygous for round, yellow peas is crossed with a homozygous round but heterozygous yellow pea plant, how many different phenotypes are their offspring expected to show?

<p>2</p> Signup and view all the answers

What do you call a situation in which one allele for a gene is not completely dominant over another allele for that gene?

<p>incomplete dominance</p> Signup and view all the answers

What type of inheritance is illustrated by a cross of a red cow with a white bull producing all roan offspring?

<p>codominance</p> Signup and view all the answers

What is the number of chromosomes in a gamete represented by?

<p>N</p> Signup and view all the answers

If an organism's diploid number is 12, what is its haploid number?

<p>6</p> Signup and view all the answers

What do gametes have for each gene?

<p>one allele</p> Signup and view all the answers

By which process are gametes produced?

<p>meiosis</p> Signup and view all the answers

What is the diagram of chromosomes created during crossing over?

<p>crossing over</p> Signup and view all the answers

During which phase do chromosomes form tetrads?

<p>prophase of meiosis I</p> Signup and view all the answers

What happens between meiosis I and meiosis II that reduces the number of chromosomes?

<p>Replication does not occur</p> Signup and view all the answers

Unlike mitosis, what does meiosis result in?

<p>four genetically different cells</p> Signup and view all the answers

In a two-factor cross where both parents are heterozygous for both traits, what would the expected phenotypic ratio be?

<p>9:3:3:1</p> Signup and view all the answers

The wide range of skin colors in humans is an example of what?

<p>polygenic traits</p> Signup and view all the answers

What is it called when human blood type alleles of A and B are equally dominant to each other and both are expressed?

<p>codominance</p> Signup and view all the answers

When the heterozygous phenotype is a combination or an intermediate of the two homozygous phenotypes, what is it called?

<p>incomplete dominance</p> Signup and view all the answers

If the sex cell of an organism has 20 chromosomes, how many chromosomes will the body cells have?

<p>40</p> Signup and view all the answers

A trait is a specific characteristic that varies from one individual to another.

<p>True</p> Signup and view all the answers

An organism with a dominant allele for a particular form of a trait will sometimes show that trait.

<p>False</p> Signup and view all the answers

When alleles segregate from each other, they join.

<p>False</p> Signup and view all the answers

The probability that a gamete produced by a pea plant heterozygous for stem height will contain the recessive allele is 100%.

<p>False</p> Signup and view all the answers

Mitosis results in two cells, whereas meiosis results in one cell.

<p>False</p> Signup and view all the answers

What are the different forms of a gene called?

<p>alleles</p> Signup and view all the answers

The principle of independent assortment states that ________ for different traits can segregate independently during the formation of gametes.

<p>genes</p> Signup and view all the answers

Red, white, and pink phenotypes in flowers called four o'clocks are an example of what?

<p>incomplete dominance</p> Signup and view all the answers

An organism's ____ have half the number of chromosomes found in the organism's body cells.

<p>gametes</p> Signup and view all the answers

What is genetics?

<p>the study of heredity</p> Signup and view all the answers

How many recessive alleles for a trait must an organism inherit in order to show that trait?

<p>two</p> Signup and view all the answers

What is the difference between incomplete dominance and codominance?

<p>In incomplete dominance, one allele is not completely dominant over another, resulting in an intermediate phenotype. In codominance, both alleles are dominant, leading to a phenotype that shows both traits.</p> Signup and view all the answers

What cross should you perform to determine whether a tall pea plant is homozygous or heterozygous for tallness?

<p>Cross the tall pea plant with a short pea plant.</p> Signup and view all the answers

When would Mendel allow the tall F1 pea plants to self-pollinate?

<p>When some are short</p> Signup and view all the answers

Linked genes are always located where?

<p>on the same chromosome</p> Signup and view all the answers

What does a Punnett square show?

<p>assort independently</p> Signup and view all the answers

Study Notes

Mendelian Genetics

  • Gregor Mendel conducted experiments using pea plants, exploring the inheritance of traits.
  • Offspring from true breeding parents with different traits are termed hybrids.
  • Genes are the fundamental chemical factors determining traits.

Principles of Inheritance

  • Traits are inherited through factors passed from parents to offspring.
  • Dominant alleles overshadow recessive alleles, as seen when tall plants crossed with short plants resulted in all tall offspring.
  • The probability of F2 plants being tall after self-pollination of tall F1 plants is 75%.

Genetic Terminology

  • Organisms with identical alleles for a particular trait are homozygous.
  • A Punnett square visually represents potential offspring genotypes but does not show actual results.
  • The Principle of Independent Assortment states that genes for different traits segregate independently during gamete formation.

Genetic Combinations

  • Gametes from a pea plant with genotype RrYY will have 2 different allele combinations.
  • Crossing heterozygous round, yellow peas (RrYy) with homozygous round peas (RRYy) yields 2 different phenotypes.

Patterns of Inheritance

  • Incomplete dominance occurs when one allele isn't completely dominant over another, resulting in a mix in heterozygous phenotypes.
  • Codominance occurs when both alleles are equally dominant and expressed, as seen in roan offspring from a red cow and a white bull.
  • Polygenic traits, such as human skin color, arise from the interaction of multiple genes.

Chromosomes and Meiosis

  • Gametes contain one allele for each gene; they are produced through meiosis, which results in four genetically distinct cells.
  • Diploid organisms have double the number of chromosomes compared to their haploid gametes.

Genetic Probability and Ratios

  • In a two-factor cross of heterozygous parents (TtYy x TtYy), the expected phenotypic ratio is 9:3:3:1.
  • The probability that a gamete from a heterozygous plant will carry a recessive allele is 50%.

Traits and Alleles

  • Traits are specific characteristics, and different gene forms are called alleles.
  • An organism must inherit two recessive alleles to express a recessive trait.
  • Additional traits can range from red, white, to pink in four o'clock flowers, serving as examples of incomplete dominance.

Key Concepts in Genetics

  • Gametes have half the chromosome number of body cells, essential for sexual reproduction.
  • Mitosis produces two identical cells, while meiosis produces four varied cells.
  • Linked genes are located on the same chromosome, influencing inherited traits.

Mendel's Experimentation

  • To determine whether a tall pea plant is homozygous or heterozygous, cross it with a short plant; offspring patterns reveal the plant's genotype.
  • If Mendel allowed tall F1 plants to self-pollinate, it was to observe whether any short plants appeared.

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Test your knowledge on Chapter 11 of Biology with flashcards that cover key concepts such as inheritance of traits, hybrids, and genes. Perfect for reinforcing your understanding of Mendelian genetics.

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