12th Grade > Biology
PRINCIPLES OF INHERITANCE AND VARIATION MCQs
Total Questions : 45
| Page 4 of 5 pages
Answer: Option B. -> At the time of fertilization
:
B
The sex of the child depends on the type of sperm that fertilises the egg. Each egg contains oneX chromosomeand a sperm may have either an X or a Y chromosome. It is a matter of chance as to which type of sperm fertilises the ovum. If the egg (having X chromosome) is fertilised by a X-bearing sperm, the resulting combination is XX i.e., female.If the egg (having X chromosome) is fertilised by a Y-bearing sperm, the resulting combination is XY i.e., male.
:
B
The sex of the child depends on the type of sperm that fertilises the egg. Each egg contains oneX chromosomeand a sperm may have either an X or a Y chromosome. It is a matter of chance as to which type of sperm fertilises the ovum. If the egg (having X chromosome) is fertilised by a X-bearing sperm, the resulting combination is XX i.e., female.If the egg (having X chromosome) is fertilised by a Y-bearing sperm, the resulting combination is XY i.e., male.
Answer: Option B. -> Tt
:
B
Most multicellular organisms have two sets of chromosomes; that is, they are diploid. These chromosomes are referred to as homologous chromosomes. If bothallelesat a gene (or locus) on the homologous chromosomes are the same, they and the organism are homozygous with respect to that gene. If the alleles for a gene are different, then organisms are heterozygous for that gene. For example, the gene for tallness can be present in three forms TT (homozygous), Tt (heterozygous), tt (homozygous).
:
B
Most multicellular organisms have two sets of chromosomes; that is, they are diploid. These chromosomes are referred to as homologous chromosomes. If bothallelesat a gene (or locus) on the homologous chromosomes are the same, they and the organism are homozygous with respect to that gene. If the alleles for a gene are different, then organisms are heterozygous for that gene. For example, the gene for tallness can be present in three forms TT (homozygous), Tt (heterozygous), tt (homozygous).
Answer: Option A. -> Anaphase-I
:
A
In anaphase-I, the two alleles of the gene get separated as homologous pair of chromosomes separate at this stage. Parallel behaviour of genes and chromosomes was first observed by Sutton and Boveri and they used chromosome movement to explain Mendel's laws.
:
A
In anaphase-I, the two alleles of the gene get separated as homologous pair of chromosomes separate at this stage. Parallel behaviour of genes and chromosomes was first observed by Sutton and Boveri and they used chromosome movement to explain Mendel's laws.
Answer: Option B. -> Indicating relative position of genes in chromosomes
:
B
Morgan conducted experiments on Drosophila related to X-linked inheritance. He suggested that the frequency of crossing over between two genes depends on distance between them.Physical crossing over during meiosis I is a normal event. The effect of this event is to rearrange heterozygous homologous chromsomes into new combinations. The term used for crossing over isrecombination. Recombination can occur between any two genes on a chromosome, the amount of crossing over is a function of how close the genes are to each other on the chromosome. If two genes are far apart, for example at opposite ends of the chromosome, crossover and non-crossover events will occur in equal frequency. Genes that are closer together undergo fewer crossing over events and non-crossover gametes will exceed the number of crossover gametes. Therefore, determination of percentage of crossing over gives an idea about the position of genes on chromosomes.
:
B
Morgan conducted experiments on Drosophila related to X-linked inheritance. He suggested that the frequency of crossing over between two genes depends on distance between them.Physical crossing over during meiosis I is a normal event. The effect of this event is to rearrange heterozygous homologous chromsomes into new combinations. The term used for crossing over isrecombination. Recombination can occur between any two genes on a chromosome, the amount of crossing over is a function of how close the genes are to each other on the chromosome. If two genes are far apart, for example at opposite ends of the chromosome, crossover and non-crossover events will occur in equal frequency. Genes that are closer together undergo fewer crossing over events and non-crossover gametes will exceed the number of crossover gametes. Therefore, determination of percentage of crossing over gives an idea about the position of genes on chromosomes.
Answer: Option C. -> YYRR × yyrr
:
C
In Mendel’s dihybrid cross, pure yellow round seeded plant (YYRR) is crossed with pure green wrinkled (yyrr) seeded plant. Here the yellow color and round shape of seeds are dominant over the green color and wrinkled shape of seeds respectively.
:
C
In Mendel’s dihybrid cross, pure yellow round seeded plant (YYRR) is crossed with pure green wrinkled (yyrr) seeded plant. Here the yellow color and round shape of seeds are dominant over the green color and wrinkled shape of seeds respectively.
Answer: Option A. -> 100%
:
A
The white-eyed female (ww) produces gametes with only (w) allele. The male fly is red-eyed and produces gametes half of which carry (R) allele while the other half carry the Y chromosome. The progeny would comprise of 50% females and 50% males. All these females would be red-eyed (Rw;red being dominant), while the males would be white-eyed. The image below will explain the inheritance pattern.
:
A
The white-eyed female (ww) produces gametes with only (w) allele. The male fly is red-eyed and produces gametes half of which carry (R) allele while the other half carry the Y chromosome. The progeny would comprise of 50% females and 50% males. All these females would be red-eyed (Rw;red being dominant), while the males would be white-eyed. The image below will explain the inheritance pattern.
Answer: Option A. -> Non-disjunction of X chromosomes
:
A
Eye colour is a sex linked trait in Drosophila with red eye colour being dominant over white eye colour. Whenred eyedmales are crossed withwhite eyedfemales, one expects white eyed males andred eyedfemales in F1generation, using the knowledge of Morgan's experiments. However, Bridges found that there could arise a situation wherein red eyed males and white eyed females are observed. He observed that such females had a chromosomal pattern XXY instead of the usual XX. Bridges explained this instance on the basis of non-disjunction of X chromosomes in femaleindividuals. Non-disjunction of X chromosomes means an absence of separation of the two homologous X chromosomes during anaphase I of meiosis. Instead, both X chromosomes move together to the same pole. The other pole obviously would receive no X chromosomes. When an egg with two X chromosomes - both containing only the alleles for white eye colour, is fertilised by a sperm carrying Y chromosome (without any allele for eye colour, since this gene is present only on X chromosome), the resultant offspring turns out to be a white eyed female (XXY).
:
A
Eye colour is a sex linked trait in Drosophila with red eye colour being dominant over white eye colour. Whenred eyedmales are crossed withwhite eyedfemales, one expects white eyed males andred eyedfemales in F1generation, using the knowledge of Morgan's experiments. However, Bridges found that there could arise a situation wherein red eyed males and white eyed females are observed. He observed that such females had a chromosomal pattern XXY instead of the usual XX. Bridges explained this instance on the basis of non-disjunction of X chromosomes in femaleindividuals. Non-disjunction of X chromosomes means an absence of separation of the two homologous X chromosomes during anaphase I of meiosis. Instead, both X chromosomes move together to the same pole. The other pole obviously would receive no X chromosomes. When an egg with two X chromosomes - both containing only the alleles for white eye colour, is fertilised by a sperm carrying Y chromosome (without any allele for eye colour, since this gene is present only on X chromosome), the resultant offspring turns out to be a white eyed female (XXY).
Answer: Option A. -> True
:
A
The chromosomal disorders are caused due to absence or excess or abnormal arrangement of one or more chromosomes.Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy. For example, Down syndrome results in the gain of extra copy of chromosome 21, i.e., the baby will have three copies of this chromosome (also called trisomy of 21st chromosome)
:
A
The chromosomal disorders are caused due to absence or excess or abnormal arrangement of one or more chromosomes.Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy. For example, Down syndrome results in the gain of extra copy of chromosome 21, i.e., the baby will have three copies of this chromosome (also called trisomy of 21st chromosome)
Answer: Option C. -> Hugo de Vries, Carl Correns and Erich Von Tschermak
:
C
In 1900, three scientists Hugo de Vries, Carl Correns and Erich Von Tschermak independently rediscovered Mendel’s results on the inheritance of characters.
:
C
In 1900, three scientists Hugo de Vries, Carl Correns and Erich Von Tschermak independently rediscovered Mendel’s results on the inheritance of characters.
Answer: Option B. -> 23
:
B
Linkage is simply the phenomenon by which adjacent genes on the same chromosome stay together and move as a group from generation to generation. It could be said that each block of genes (which basically means a chromosome) constitutes a linkage group. Hence the haploid number of chromosomes would generally be equal to the number of linkage groups in an organism. So we can say that there are 23 linkage groups in man which is equal to the haploid number of chromosomes.
:
B
Linkage is simply the phenomenon by which adjacent genes on the same chromosome stay together and move as a group from generation to generation. It could be said that each block of genes (which basically means a chromosome) constitutes a linkage group. Hence the haploid number of chromosomes would generally be equal to the number of linkage groups in an organism. So we can say that there are 23 linkage groups in man which is equal to the haploid number of chromosomes.
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