Q&A Hero

Q: When Mendel crossed heterozygotes for flower color and seed color, what proportion of the offspring had both dominant phenotypes? A) 3/4 B) 3/16 C) 1/3 D) 1/16 E) 9/16

Q: In Mendel's pea plants, yellow seeds are dominant to green seeds. Purple flowers are dominant to white flowers. Use Y and y for the seed color alleles and P and p for the flower color alleles. Flower color and seed color assort independently. If a plant that is heterozygous for both flower color and seed color genes is self-fertilized, what proportion of the offspring will have one of the dominant phenotypes, either the seed color or flower color, but not both? A) 6/64 B) 6/32 C) 6/16 D) 9/32 E) 9/16

Q: In Mendel's pea plants, yellow seeds are dominant to green seeds. Purple flowers are dominant to white flowers. Use Y and y for the seed color alleles and P and p for the flower color alleles. Flower color and seed color assort independently. A true-breeding plant with green seeds and white flowers is crossed to a plant that is heterozygous for the genes for both phenotypes. What is the probability that the cross will yield a plant with green seeds and white flowers? A) 3/16 B) 3/32 C) 1/32 D) 1/16 E) 1/4

Q: In Mendel's pea plants, yellow seeds are dominant to green seeds. Purple flowers are dominant to white flowers. Use Y and y for the seed color alleles and P and p for the flower color alleles. Flower color and seed color assort independently. A plant of unknown genotype with yellow seeds and purple flowers is crossed to a plant with green seeds and white flowers. The offspring all have yellow seeds, but some have purple flowers, and some have white flowers. What is the genotype of the yellow-seeded, purple-flowered plant? A) YyPp B) YYPp C) YyPP D) YYPP E) Yypp

Q: In humans, freckles are dominant to no freckles, and unattached earlobes are dominant to attached earlobes. Two individuals who both have freckles and unattached earlobes have a child with no freckles and attached earlobes. What are the genotypes of the parents? (F = freckles; E = unattached earlobes) A) FFEE x ffee B) Ffee x FFEE C) FfEe x FfEe D) FFEE x FFEe E) ffee x ffee

Q: In order to track the inheritance of two characters, you would need to do a: A) monohybrid cross. B) dihybrid cross. C) trihybrid cross. D) true-breeding cross.

Q: In order to track the inheritance of a single character, you would need to do a: A) monohybrid cross. B) dihybrid cross. C) trihybrid cross. D) true-breeding cross.

Q: Let S = smooth pea and s = wrinkled pea; Y = yellow pea and y = green pea. What pea phenotype would be produced by the genotype SsYy? A) smooth, yellow B) smooth, green C) wrinkled, yellow D) wrinkled, green

Q: Let S = smooth pea and s = wrinkled pea; Y = yellow pea and y = green pea. What are the different possible genotypes of the gametes produced by a plant that is heterozygous for both characters? A) All will be SsYy. B) Ss, Yy C) S, s, Y, y D) SY, Sy, sY, sy E) SY, sy

Q: When Mendel crossed plants and followed two traits (a dihybrid cross), he saw a 9:3:3:1 ratio of traits in the F2generation. What did he conclude? A) The two traits affect each other's transmission. B) Dominant traits are always more common than recessive ones. C) In meiosis, one allele of each gene is passed to each gamete. D) The transmission of one trait is unaffected by the other.

Q: The Law of Independent Assortment states that: A) in meiosis, crossing over creates genetically diverse gametes. B) in fertilization, the combining of sperm and eggs is random. C) generation of male and female gametes must occur in separate organisms. D) in any dihybrid cross, it is possible to get any combination of phenotypes. E) in gamete formation, gene pairs are transmitted independently of each other.

Q: What is the physical basis for the independent assortment observation that Mendel made? A) Male and female gametes are produced in separate organs in separate individuals. B) Sister chromatids do not separate until meiosis II. C) There are two chromosome divisions in meiosis. D) Homologous chromosomes are randomly aligned and separated during meiosis. E) Recombination (crossing over) occurs in meiosis.

Q: In humans, "unattached" earlobes are dominant over "attached" earlobes. Widow's-peak hairline is dominant over non-widow's-peak hairline. Use E and e for the earlobe phenotype alleles and W and w for the hairline phenotype alleles. A woman with unattached earlobes and a widow's peak and a man with attached earlobes and a widow's peak have a child. The child has attached earlobes and a non-widow's-peak hairline. What are the genotypes of the parents? A) EEWW and eeww B) EeWw and eeWw C) EEWW and eeWw D) EeWw and EeWW E) EeWw and eeww

Q: Which of the following represents a dihybrid cross? A) YYyy x PPpp B) YY x pp C) YyPp x YyPp D) YP x Yp E) Yp x YY

Q: In humans, "unattached" earlobes are dominant over "attached" earlobes. Widow's-peak hairline is dominant over non-widow's-peak hairline. Use E and e for the earlobe phenotype alleles and W and w for the hairline phenotype alleles. A woman and a man, both with genotype EeWw, have a child. What is the probability that the child will have attached earlobes and a widow's peak? A) 1/16 B) 9/16 C) 1/3 D) 3/4 E) 3/16

Q: In Mendel's pea plants, yellow seeds are dominant to green seeds. If a true-breeding green-seed-producing plant is crossed to a heterozygous yellow-seed-producing plant, what percentage of offspring produces green seeds? A) 10 percent B) 50 percent C) 33 percent D) 25 percent E) 100 percent

Q: When two identical alleles for a character are present, the genotype is referred to as: A) heterozygous. B) homozygous. C) dominant. D) recessive.

Q: Dimpled cheeks are dominant to undimpled cheeks. If there exists a 50 percent chance that a child will have dimpled cheeks, the parental genotypes must be: A) dd and dd. B) Dd and dd. C) DD and Dd. D) Dd and Dd. E) DD and dd.

Q: If an individual exhibits a recessive trait, which of the following statements can you be sure of? A) The phenotype for this trait is different from the phenotype of the homozygous dominant genotype for this trait. B) The genotype of this trait will be heterozygous. C) Both parents of this individual had the same genotype for this trait. D) Any siblings of this individual will have the same phenotype for this trait. E) Any children this individual has will always exhibit the trait, regardless of the genotype of the other parent.

Q: The Law of Segregation states that: A) gene pairs assort independently of each other during gamete formation. B) differing characters in organisms result from two alleles that separate in gamete formation, such that each gamete gets only one of the two alleles. C) differing characters are the result of either the homozygous dominant or the homozygous recessive condition. D) phenotypes are always determined by genotypes. E) one allele of a pair must always be dominant and the other must always be recessive.

Q: Widow's-peak hairline in humans is dominant to non-widow's-peak hairline. If a person has a widow's-peak hairline, what is his or her genotype? A) The genotype must be homozygous recessive. B) The genotype is either homozygous dominant or homozygous recessive. C) The genotype must be heterozygous. D) The genotype is either heterozygous or homozygous dominant. E) The genotype must be homozygous dominant.

Q: The genotype Ff is an example of a: A) trait controlled by multiple genes. B) homozygous genotype. C) monohybrid genotype. D) heterozygous genotype. E) dihybrid genotype.

Q: In Mendel's pea plant experiments, in order for him to have observed a 3:1 phenotypic ratio in the F2generation, which of the following must be true? A) The two alleles of a pair separate in gamete formation. B) The pairs of alleles must be either homozygous dominant or homozygous recessive. C) Both alleles of a pair must go into each gamete together. D) Both of the F1parents must be breed true.

Q: When a yellow-seeded pea plant with the genotype Yy produces gametes, what will be the genotype(s) of the gametes? A) All will be YY. B) All will be Yy. C) They will be either all Y or all y. D) Half will be YY, and half will be yy. E) Half will be Y, and half will be y.

Q: Cystic fibrosis (CF) is caused by a recessive allele. A child has CF, even though neither of his parents has CF. This couple also has a child who does not have CF. What is the probability the unaffected child is heterozygous? A) 2/3 B) 1/3 C) 1/2 D) 3/4 E) 1/4

Q: Cystic fibrosis (CF) is caused by a recessive allele. A child has CF, even though neither of his parents has CF. Which of the following describes the genotypes of the parents? A) One is homozygous dominant for the CF gene, and the other is heterozygous. B) One is homozygous recessive for the CF gene, and the other is heterozygous. C) They are both homozygous recessive for the CF gene. D) They are both homozygous dominant for the CF gene. E) They are both heterozygous for the CF gene.

Q: A and a are dominant and recessive alleles, respectively, of the same gene. Which genotype(s) would result in an individual with the recessive phenotype? A) Aa and aa B) AA and aa C) Aa only D) AA only E) aa only

Q: A and a are dominant and recessive alleles, respectively, of the same gene. Which genotype(s) would result in an individual with the dominant phenotype? A) AA and aa B) Aa and aa C) only AA D) AA and Aa E) only Aa

Q: Mendel crossed true-breeding pea plants and found the dominant trait always appeared in the F1generation, but it appeared in a ________ ratio of dominant to recessive in the F2generation. A) 1:3 B) 1:2 C) 3:1 D) 1:1

Q: Before Mendel, people had observed inheritance of dominant and recessive traits by following many generations of plants and animals. What was different about Mendel's work? A) He used a plant that had never been cultivated before. B) He kept careful count of his results, including mathematical analysis. C) His results were immediately accepted and applied to other studies. D) He followed more generations than anyone else. E) He did both cross- and self-fertilizations.

Q: The D gene controls pea plant height. The DD and dd genotypes confer tall and dwarf phenotypes, respectively. What is the relationship between D and d? A) They are two different plant chromosomes. B) They are two different genes on the same chromosome. C) They are alleles of the same gene. D) They are two possible homozygous genotypes. E) They are two possible heterozygous genotypes.

Q: Mendel wanted to make sure his starting plants bred true, meaning the: A) seeds would always sprout. B) peas would always be green. C) phenotypes of the offspring in each generation could not be predictable. D) phenotypes of the offspring in each generation were always the same as the parent. E) phenotypes of the offspring in each generation would sometimes look like the male parent and sometimes look like the female parent.

Q: Mendel postulated that individuals have genetic elements that exist in pairs, which determine a single phenotype. What do we now know these pairs of elements to be? A) two haploid sets of chromosomes B) two alleles of a gene on homologous chromosomes C) pairs of sister chromatids D) pairs of centromeres E) a sperm and an egg

Q: The seeds in a pod of one of Mendel's pea plants are: A) produced only when a plant is cross-fertilized. B) genetically identical to each other but different from other peas in other pods. C) produced only when a plant is self-fertilized. D) each the result of a separate fertilization event. E) genetically identical to each other and all other peas from that plant.

Q: What is the term for an observable trait of an organism? A) element B) phenotype C) hybrid D) genotype E) allele

Q: Which of the following was not one of Mendel's main inferences from his research? A) The basic units of genetics are material elements. B) The genetic material elements come in pairs. C) Genes are lengths of DNA. D) The genetic material elements can retain their character through many generations. E) The genetic material elements separate during the formation of gametes.

Q: What is the advantage of ova production resulting in one egg and three polar bodies? A) This allows the egg to receive most of the cytoplasm. B) This reduces egg size by distributing most of the cytoplasm to the polar bodies. C) This allows the egg to receive all the chromosomes. D) This removes Golgi complex, lysosomes, and other organelles from the egg. E) This creates more polar bodies, which are the cells that will actually be fertilized.

Q: Which of the following is true about both sperm and egg production? A) Initiation of meiosis is continuous after puberty. B) All cells that result from meiosis function as gametes. C) All resulting gametes are the same size. D) Millions of mature gametes are produced daily. E) All resulting gametes are haploid.

Q: What is the fate of sperm that are never released? A) They are stored indefinitely. B) Their cell cycles are stopped in meiosis I. C) They continue dividing by mitosis to produce more mature sperm. D) They are destroyed by the body's immune system. E) They combine to make diploid spermatogonia.

Q: In the process of egg production, one cell produced during meiosis will become the egg, and the other three will become: A) primary oocytes. B) oogonia. C) primary bodies. D) polar bodies.

Q: A human egg contains: A) 23 autosomes and an X or a Y chromosome. B) 22 autosomes and an X or a Y chromosome. C) 46 chromosomes, as 23 pairs. D) 22 pairs of autosomes and two X chromosomes. E) 22 autosomes and one X chromosome.

Q: In a human female, what happens to the collection of oocytes in the ovaries once puberty begins? A) The oocytes all mature into eggs as soon as puberty is reached. B) Ovulation stimulates all of the oocytes to complete meiosis II. C) One oocyte per month matures and completes meiosis I. D) One oocyte per month matures and completes meiosis I and meiosis II. E) All ooctyes are expelled from the ovaries to complete meiosis II.

Q: What would the consequence be if spermatogonia were not stem cells? A) Only a limited quantity of sperm could be produced by males, and then no more could be produced. B) Sperm would be diploid rather than haploid. C) Sperm would have to be produced by mitosis instead of meiosis. D) Mature spermatids would make more sperm by meiosis.

Q: In gamete formation, the starting cells in females are the ________, and the starting cells in males are ________. A) primary oocytes; prmary spermatocytes B) primary spermatocytes; primary oocytes C) oogonia; spermatogonia D) spermatogonia; oogonia E) ooctyes; spermatids

Q: In birds, the female carries an unmatched pair of chromosomes (denoted WZ), corresponding roughly to the XY chromosomes in mammalian males, and male birds carry a matched set of chromosomes (denoted WW), corresponding to the pair of XX chromosomes in mammalian females. Therefore, in birds the ________ chromosome determines the sex of the offspring, and it is gametes from the ________ parent that determine sex. A) Z; male B) Z; female C) W; female D) W; male E) W; either male or female

Q: A gamete from a human male contains: A) 23 autosomes and an X chromosome. B) 22 autosomes, one X chromosome, and one Y chromosome. C) 23 autosomes and either an X or a Y chromosome. D) 23 autosomes and a Y chromosome. E) 22 autosomes and either an X or a Y chromosome.

Q: What is an autosome? A) one of the non-sex chromosomes B) a chromosome that confers male or female sex C) a Y chromosome D) an X chromosome

Q: In a human cell that is haploid, how many chromosomes are there? How many are autosomes, and how many are sex chromosomes? A) 45 chromosomes: 44 autosomes and 1 sex chromosome B) 46 chromosomes: 44 autosomes and 2 sex chromosomes C) 23 chromosomes: 22 autosomes and 1 sex chromosome D) 11 chromosomes: 11 autosomes and no sex chromosomes E) 12 chromosomes: 11 autosomes and 1 sex chromosome

Q: Imagine you start a population of 1 million bacteria from a single bacterial cell. Now imagine that a population this large is started from a male and female housefly. How would these two populations differ? A) The cells of the bacterial population would be larger on average than the cells that make up the houseflies. B) Individuals of the housefly population would differ genetically from each other much more than would cells of the bacterial population. C) No cells of the housefly population would ever divide by meiosis, but some cells of the bacterial population would divide by meiosis. D) The cells of the bacterial population would differ genetically from each other much more than would individuals of the housefly population. E) No cells of the bacterial population would ever divide by binary fission, but some cells of the housefly population would divide by binary fission.

Q: What factors produce genetic diversity in bacteria? A) crossing over B) mitosis C) crossing over and independent assortment D) mutation and gene transfer

Q: If a diploid cell has 12 chromosome pairs, how many different combinations of chromosomes are possible in gametes after meiosis? A) 1220 B) 122 C) 212 D) 1012 E) 1212

Q: If a 2n cell has three chromosome pairs, how many different combinations of chromosomes are possible in gametes after meiosis? A) 16 B) 32 C) 8 D) 64 E) 36

Q: What is the result of independent assortment during meiosis? A) The cells that result have either all maternal or all paternal chromosomes. B) Parts of homologous chromosomes are exchanged. C) Both copies of a sister chromatid pair end up in the same gamete. D) The cells that result are genetically identical to each other. E) Genetically diverse gametes are produced.

Q: Which of the following processes contributes least to genetic diversity? A) crossing over B) combining of gametes from two different individuals C) independent assortment of chromosomes at the metaphase plate D) duplication of DNA

Q: What is the result of recombination (crossing over) during meiosis? A) It ensures retention of genetic information and helps to preserve cell characteristics. B) It binds homologous chromosomes tightly, so they do not accidentally separate. C) It eliminates unused genes by removing them. D) It allows the cell to complete DNA replication. E) It creates chromosomes that are a new combination of paternal and maternal material.

Q: What process produces genetic diversity through random distribution of chromosomes? A) alignment of the metaphase plate to one side instead of in the middle B) cytokinesis C) independent assortment D) recombination E) crossing over

Q: If a cell has a haploid number of 5, during mitosis there will be ________ chromosomes at metaphase, ________ chromosomes at anaphase, and ________ chromosomes per daughter cell at telophase. A) 5; 10; 5 B) 5; 5; 5 C) 10; 20; 10 D) 10; 10; 10 E) 10; 10; 5

Q: In metaphase I ________ are aligned along the metaphase plate, and in metaphase II ________ are aligned along the metaphase plate. A) pairs of sister chromatids; homologous chromosomes B) maternal chromosomes; paternal chromosomes C) homologous chromosomes; tetrads D) homologous chromosomes; pairs of sister chromatids

Q: A cell contains eight chromosomes at the end of prophase I. How many chromosomes will be in each daughter cell at the end of prophase II? A) 4 B) 8 C) 16 D) 32

Q: Imagine that a species has eight chromosomes (four homologous pairs). If some event occurred that prevented meiosis from occurring after replication, how many chromosomes would this species have after two generations? A) 64 B) 8 C) 32 D) 16 E) 4

Q: In the process of crossing over: A) sister chromatids separate. B) maternal chromosomes assort independently of paternal chromosomes. C) homologous chromosomes separate. D) sister chromatids exchange genetic material. E) non-sister chromatids of homologous chromosomes exchange genetic material.

Q: Which of the following occur during telophase I? A) Cytokinesis produces four haploid gametes. B) Sister chromatids separate and move to opposite poles. C) Cytokinesis produces two cells that will each go through meiosis II. D) Homologous chromosomes separate. E) One cell divides two times, without interruption, into four cells.

Q: Meiosis II is essentially the same as mitosis except that the outcome produces cells that are: A) diploid. B) somatic. C) autosomal. D) genetically identical to each other. E) haploid.

Q: The cells at the end of meiosis I are not ready to function as gametes. Why not?A) They have the right number of chromosomes but no cytoplasm.B) They have the right number of chromosomes but too much cytoplasm.C) They are haploid, but the chromosomes are still in duplicated form.D) The chromosomes have divided, but there has been no cytokinesis.E) The homologous chromosomes have not yet separated.

Q: What event occurs in both anaphase of mitosis and anaphase II of meiosis II? A) Cytokinesis ends. B) Homologous chromosomes separate. C) Chromatin decondenses. D) Homologous chromosomes pair. E) Sister chromatids separate.

Q: Homologous chromosomes pair up to form a structure called a: A) sister chromatid. B) tetrad. C) homologue. D) haploid.

Q: Which of the following occurs during anaphase I? A) Homologous chromosomes are moved to the metaphase plate. B) Sister chromatids are separated. C) Crossing over begins. D) Homologous chromosomes are separated. E) Cytokinesis occurs.

Q: Crossing over occurs during which stage of meiosis? A) telophase I B) metaphase II C) anaphase II D) prophase II E) prophase I

Q: You have homologous pairs of chromosomes in each of your cells. In what way are these pairs of chromosomes identical? A) They have exactly the same genes. B) They both come from the same parent. C) They have genes for the same traits. D) They will stay together during meiosis.

Q: In mitosis, cells duplicate their chromosomes once and divide once. In meiosis, cells duplicate their chromosomes ________ and divide ________. A) once; once B) twice; once C) twice; twice D) once; twice

Q: Cells that are ________ possess a single set of chromosomes. A) diploid B) haploid C) zygotes D) somatic

Q: If the chromosome number were not halved when gametes are produced, what would be the result of fertilization? A) They zygote would have the same number of chromosomes as the parents. B) The zygote would have double the number of chromosomes as the parents. C) The zygote would have half the number of chromosomes as the parents. D) The zygote would undergo meiosis again to halve the number of chromosomes.

Q: If a eukaryotic cell has 20 chromosomes and it undergoes meiosis, how many cells will result, and how many chromosomes will they contain? A) 4 cells, each with 20 chromosomes B) 4 cells, each with 10 chromosomes C) 2 cells, each with 10 chromosomes D) 2 cells, each with 20 chromosomes

Q: A 2n cell from an organism has 40 chromosomes. How many chromosomes would be in a haploid gamete from this organism? A) 46 B) 80 C) 10 D) 40 E) 20

Q: How are the products of meiosis and the products of mitosis different? A) The products of mitosis are gametes. B) The products of mitosis are always haploid. C) The products of meiosis are genetically identical to each other. D) The products of meiosis are gametes. E) The products of meiosis are always diploid.

Q: The products of meiosis are: A) two diploid cells. B) four haploid cells. C) four diploid cells. D) two haploid cells.

Q: How many chromosomes are in a human gamete? A) 43 B) 42 C) 26 D) 23 E) 46

Q: The fertilization of an egg by a sperm produces a cell called a/an: A) ovum. B) gamete. C) zygote. D) oocyte.

Q: Refer to the figure below, and then answer the question that follows.A difference between spermatogenesis and oogenesis is:A) sperm are produced after meiosis II, but an egg is produced after meiosis I.B) spermatids all have the same amount of genetic material, but polar bodies have less genetic material then the egg.C) meiosis produces four sperm but only one egg.D) sperm are haploid, but eggs are diploid.E) a primary oocyte has more genetic material than a primary spermatocyte.

Q: Refer to the figure below, and then answer the question that follows.If crossing over occurs as shown in the figure above, which of the following is true?A) Sister chromatids exchange genetic material during crossing over.B) The result of crossing over is four genetically identical chromatids.C) The result of crossing over is four genetically different chromatids.D) The resulting chromatids all have a combination of maternal and paternal genetic material.E) The resulting chromatids either have only maternal genetic material or paternal genetic material.