Chpt 14 chromosomal Basis Of Inheritance Flashcards
- Which scientist’s work was rediscovered shortly before the chromosome theory of inheritance gained widespread acceptance?* (a) Gregor Mendel* (b) Thomas Hunt Morgan* (c) Calvin Bridges * (d) Theodore Boveri *
*Answer:** (a)Explanation: The source mentions that shortly after Mendel’s work was rediscovered it became widely assumed that genes were located on chromosomes.
- What innovation in the 1880s enabled scientists to identify and track chromosome movement during cell division (a) Genetic sequencing(b) Electrophoresis(c) Microscopy and staining techniques (d) PCR
*Answer:** (c)Explanation: The source explicitly states that advancements in microscopy and staining techniques in the 1880s facilitated the identification and tracking of chromosomes.
- The chromosome theory of inheritance explains how the transmission of chromosomes accounts for: *(a) Protein synthesis(b) Mendelian patterns of inheritance (c) DNA replication (d) Enzyme function
Answer: (b)Explanation: The source states that the chromosome theory of inheritance describes how chromosome transmission explains Mendelian inheritance patterns.
- Which pair of scientists independently proposed the chromosome theory of inheritance in 1902-1903? (a) Watson and Crick (b) Mendel and Darwin(c) Boveri and Sutton (d) Morgan and Bridges
Answer: (c)Explanation: The source names Theodore Boveri and Walter Sutton as the scientists who independently proposed the theory.
- During meiosis each homologue segregates into?(a) The parent cell (b) One of the two daughter nuclei (c) The cytoplasm (d) The cell membrane
Answer: (b)Explanation: The source indicates that homologues segregate into one of the two daughter nuclei during meiosis.
- Which type of chromosomes segregate independently during gamete formation? (a) Homologous chromosomes (b) Non-homologous chromosomes(c) Sister chromatids (d) Sex chromosome
*Answer:** (a)Explanation: The source specifies that homologous chromosomes segregate independently during gamete formation.
- Mendel’s law of independent assortment can be explained by the behavior of:(a) Homologous chromosomes(b) Non-homologous chromosomes (c) Sister chromatids(d) Sex chromosomes*
Answer:** (b)*Explanation:** The source explains that the independent assortment of non-homologous chromosomes during meiosis explains Mendel’s law.
- The first conclusive evidence that genes are parts of chromosomes came from studies of: (a) Autosomal genes(b) Sex chromosomes (c) Mitochondrial DNA (d) Ribosomal RNA
Answer:** (b)Explanation:** The source highlights that the study of sex chromosome transmission provided the first definitive proof of genes residing on chromosomes.
- In some insect species the unpaired chromosome in males is called the: (a) Y chromosome(b) X chromosome (c) Autosome (d) Homologue
Answer:** (a)Explanation:** The source refers to the unpaired chromosome in males of some insect species as the y chromosome.
- What is the chromosome denoted as that pairs with the X chromosome in some species? (a) X chromosome(b) Z chromosome(c) Y chromosome (d) W chromosome
Answer: (c)*Explanation:** The source identifies the chromosome that pairs with the X chromosome as the Y chromosome.
- In the XX-XY sex determination system the female is the: * (a) Heterogametic sex (b) Homogametic sex (c) Sterile sex(d) Dominant sex
Answer:** (b)Explanation:** The source describes the female as the homogametic sex because they produce only one type of gamete (X-bearing).
- In the XX-XY system the male is the(a) Homogametic sex(b) Heterogametic sex(c) Recessive sex(d) Sterile sex
Answer:** (b)Explanation:** The source labels the male as the heterogametic sex due to their production of two types of gametes (X-bearing and Y-bearing).
- What is the expected sex ratio at fertilization in the XX-XY system with random gamete union?(a) 2:1(b) 1:2(c) 1:1(d) 3:1
Answer:** (c)Explanation:** The text indicates a 1:1 sex ratio due to equal numbers of X- and Y-bearing sperm.
- Chromosomes other than sex chromosomes are called:(a) Allosomes(b) Heterosomes (c) Autosomes(d) Homosomes
Answer:** (c)Explanation:** The source uses the term “autosomes” to refer to chromosomes other than sex chromosomes.
- Which chromosome carries few genes other than those related to male determination?(a) X chromosome(b) Y chromosome(c) Autosomes (d) All of the above
nswer:** (b)*Explanation:** The source mentions that the Y chromosome primarily contains genes related to male determination.
- The wildtype eye color in *Drosophila (a) White(b) Red(c) Brown(d) Yellow
Answer:** (b)Explanation:** The passage states that the wildtype eye color is a combination of red and brown pigments
- The white-eye mutation in Drosophila results in: (a) Increased pigment production(b) A metabolic block affecting pigment production(c) Enhanced eye development(d) No change in eye color
Answer:** (b)Explanation:** The source describes the white-eye mutation as a metabolic block knocking out both red and brown pigments.
- In Morgan’s initial cross what was the phenotype of the F1 generation? (a) All white eye$(b) All red eye (c) Half red eyes half white eye(d) Mostly white eyes
Answer:** (b)Explanation:** The text indicates that all F1 progeny from the initial cross (red-eyed female x white-eyed male) had red eyes.
- What was unusual about the white-eyed phenotype in Morgan’s F2 generation?(a) It was only observed in females(b) It was only observed in males(c) It was equally distributed between males and females (d) It was not observed at all
Answer:Explanation: The source highlights that all the white-eyed flies in the F2 generation were male.
- When Morgan crossed white-eyed females with wildtype males what were the phenotypes of the offspring?(a) All wildtype females and white-eyed males(b) All white-eyed females and wildtype males(c) All offspring had red eyes (d) All offspring had white eyes
Answer:** (a)Explanation: The passage notes that this reciprocal cross resulted in all female offspring having wildtype eyes and all males having white eyes.
- Where is the allele for white eyes in Drosophila located? (a) Y chromosome (b) X chromosome (c) Autosome (d) Mitochondria
Answer: (b) Explanation: The source explains that the different results in reciprocal crosses led Morgan to realize that the allele for white eyes resided on the X chromosome.
- What term describes a gene located on the X chromosome? (a) Y-linked (b) Autosomal (c) X-linked (d) Mitochondrial
Answer: (c) Explanation: The term “X-linked” specifically refers to genes present on the X chromosome as stated in the source.
- Which phenomenon did Calvin Bridges propose to explain exceptional offspring in Morgan’s crosses? (a) Crossing over (b) Independent assortment (c) Nondisjunction (d) Segregation
Answer: (c) Explanation: The text explains that Bridges attributed the exceptional offspring (white-eyed females and red-eyed males) to nondisjunction of the X chromosomes during meiosis.
- What is nondisjunction? (a) The normal separation of chromosomes during meiosis. (b) The failure of chromosomes to separate properly during meiosis (c) The exchange of genetic material between homologous chromosomes. (d) The independent assortment of chromosomes.
Answer: (b) Explanation: The source defines nondisjunction as the failure of two X chromosomes to separate during meiosis in the mother.