Damages and errors in the DNA can cause___________

Most common autosomal trisomy at birth is ________.

When one or more pieces of chromosome doubles and reunites at wrong sites it is called:

Mutations among members of a species arise due to:

"In chromosomal mutation the change involves in a particular part of chromosome so that a number of genes are also affected ". Whether this is: 

Evolution is the process by which large populations of species change over generations.
Genetic variations govern these changes. Genetic variations can arise from gene mutations or from genetic recombination (a normal process during which genetic material is rearranged when a cell is preparing to divide).
These variations often alter gene activity, or protein function, which may introduce different traits in an organism.
If a trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be passed to subsequent generations thus playing a role in evolution.

Additional information: The two important types of mutations are gene mutations, which can either be point mutations (happening in a single nucleotide) or
frameshift mutations (when a nucleotide or nucleotides are inserted/ deleted), and chromosomal mutations, which causes changes in the structure/ number of the entire chromosome

Concept of a sudden genetic change that breeds true in an organism is visualized as:

The concept of sudden genetic change, which breeds true in an organism is visualized as a mutation. Any sudden or spontaneous change in character which is inheritable is known as mutation. It is defined as the changing of the structure of a gene, resulting in a variant form which may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes.

Which is the INCORRECT statement regarding mutation?

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A mutation is a change in the DNA sequence of an organism. Mutations can result from errors in DNA replication during cell division, exposure to mutagens or a viral infection. Germline mutations (that occur in eggs and sperm) can be passed on to offspring, while somatic mutations (that occur in body cells) are not passed on.
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Mutations may or may not produce detectable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutation is the ultimate source of all genetic variation, providing the raw material on which evolutionary forces such as natural selection can act.
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Generally, the mutations are:

Mutations are the sudden or induced change that caused the change in the DNA sequences. This leads to the change in the expression of the gene. So mutations are harmful most of the times. Mutation is of two types on the basis of genotype of allele i.e., recessive and dominant.

Mutations occurring due to errors in chromosome duplication during the process of gametogenesis and crossing over is by:

 

Errors during meiosis can alter the number of chromosomes in cells and lead to genetic disorders.
Inherited disorders can arise when chromosomes behave abnormally during meiosis. Chromosome disorders can be divided into two categories: abnormalities in chromosome number and chromosome structural rearrangements. Because even small segments of chromosomes can span many genes, chromosomal disorders are characteristically dramatic and often fatal.
nondisjunction, which occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis. The risk of nondisjunction increases with the age of the parents.

“Point Mutations” involve:

A point mutation is a genetic mutation where a single nucleotide base is changed, inserted or deleted from a DNA or RNA sequence of an organism's genome. Point mutations have a variety of effects on the downstream protein product—consequences that are moderately predictable based upon the specifics of the mutation. These consequences can range from no effect (e.g. synonymous mutations) to deleterious effects (e.g. frameshift mutations), with regard to protein production, composition, and function.

Cystic fibrosis occurs due to?

Cystic fibrosis is a disorder that damages your lungs, digestive tract and other organs. It's an inherited disease caused by a defective gene that can be passed from generation to generation. Cystic fibrosis affects the cells that produce mucus, sweat and digestive juices.
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¶Cystic fibrosis is inherited in an autosomal recessive manner.^[1] It is caused by the presence of mutations in both copies of the gene for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Those with a single working copy are carriers and otherwise mostly healthy. CFTR is involved in the production of sweat,digestivefluids, and mucus.
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Examples of chromosomal mutations are ________.

A chromosome mutation is an unpredictable change that occurs in a chromosome. These changes are most often brought on by problems that occur during meiosis (division process of gametes) or by mutagens (chemicals, radiation, etc.). Chromosome mutations can result in changes in the number of chromosomes in a cell or changes in the structure of a chromosome. Unlike a gene mutation which alters a single gene or larger segment of DNA on a chromosome, chromosome mutations change and impact the entire chromosome.
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• Chromosome mutations are alterations occurring in chromosomes that typically result from errors during nuclear division or from mutagens.
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• Chromosome mutations result in changes in chromosome structure or in cellular chromosome numbers.
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• Examples of structural chromosome mutations include translocations, deletions, duplications, inversions, and isochromosomes.
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• Abnormal chromosome numbers result from nondisjunction, or the failure of chromosomes to separate correctly during cell division.
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• Examples of conditions that result from abnormal chromosome numbers are Down syndrome and Turner syndrome.
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• Sex chromosome mutations occur on either the X or Y sex.
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Cri-du-chat syndrome occurs as a result of?

Cri du chat syndrome is a rare genetic disorder caused by a missing section on a particular chromosome known as Chromosome 5. Sometimes, material from another chromosome is missing as well. Around one in every 50,000 or so babies is diagnosed with this disorder.
¶Cri du chat syndrome is a chromosomal disorder caused by a partial deletion (monosomy) of a varying length of the short arm (p) of chromosome 5. Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual.
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¶Cri-du-chat syndrome is caused by a deletion of the end of the short (p) arm of chromosome 5. This chromosomal change is written as 5p-. The size of the deletion varies among affected individuals; studies suggest that larger deletions tend to result in more severe intellectual disability and developmental delay than smaller deletions.

What is the evolutionary purpose of cells that undergo crossing over?

crossing over provides genetic diversity in specious which is the major cause of process of evolution.

1. Process of evolution.
2. Construction of genetic maps.
3. Production of new gene combination

Mutation occurs at the time of?

mutation can be occur when the cell are in dividing phase or non dividing phase.
mutation occurs naturally or artificially.
in cell division of meiosis , during prophase one there is change in the segment of chromosomes cases mutation due to which the progeny is differ from the parents.
In DNA replication due to some chemical mutagen , there is miss paring or wrong of base pair causes the mutation.

Which of the following does not cause variation

The variation caused by change in the number and location of genes which affect the individual genotypically and phenotypically.