KPK Board 12th Class Biology Ch 22 Inheritance Short Questions Answers

Heredity:

The ambulance of offspring to their parents is called heredity; it is responsible for continuity of life forms.

inheritance the transfer of characteristics from parents to offspring is known as inheritance.

variations in the difference in the members of the same species are called variations in shape height habits.

Then it is a branch of Biology that deals with the study of inheritance variations and the factors controlling them.

the term gene was for the first time used by Johnson gene is the basic unit of biological information and their informations are in form of chemical quotes on DNA  genes are segment of nucleic acid consisting of a specific sequence and number of amino acids

Function genes determine the expression of certain characteristics of the genome; the complete set of genetic material in a chromosome set of individuals is called its genome function; it controls the characteristics of growth and development from zygote to adult.

the alternative form of a gene is called allele it is also called alilo moreph

formation alleles are formed as a result of mutation significant alleles cause variations.

the sudden heritable change in the genetic material or an organism is called mutation mutagens by mutation causing agent is called mutagen mutant the organism in which mutation  the sudden heritable change in the genetic material or an organism is called mutation mutagens by mutation causing agent is called mutagen mutant the organism in which mutation occur is called mutant.

gregor John Mendel contributed a lot in the field of genetics that is why he is known as the father of genetics research on garden pea open a new avenue in the field of genetics experiments and result is started the pattern of Inheritance of various characteristics in garden pea and record the result in short he laid the foundation of genetics.

mental success was mainly due to following two reasons his approach was mathematical he studied a single character at a time and record the results choice his choice of experimentally material material also let him to success Garden  pea following advantage its life cycle is short it can be cultivated in unlimited areas it produces a large number of varieties it produces a large number of seeds

when are member allele` as F1 and in method mathematica.

P1 ……………………..Tallxdwarf

TTxtt

Gametes         Tt x tt

F1……………………….Tt

Mendel studied seven different characters in garden pea plant these are

seed shaped round wrinkle

seed  colour yellow green

flower colour violet white

pod shaped full constructed

pod colour green yellow

flower position axial terminal

stem height tall Dwarfs

it is the character that dominates the phenotype’s physical appearance.

save it is a character which is masked in the presence of a dominant gene it can only Express itself when the fare is composed of only recessive genes.

Hybrid offspring that are reserved from two parents with different characters are called hybrid.

Genotype the genetic makeup of a character is known as no type TT Tt is genotype for tallness.

homozygousWhen both the genes of the allele pair are same the condition is called homozygousTT tt  heterozygous at mean differentWhen both the dangers of allele pair are not the same the condition is known as heterozygous.

This law states in a cross of pure breeding parents having contrasting characters only one form of straight will appear in the next generation that rate is called the dominant trait.

monohybrid the study of a single character at a time is called monohybrid cross study of plant height dihybrid the study of two characters at a time is known as dihybrid cross shape and colour of seed pure breeding your breathing organism have certain biological traits which are passed onto all subsequent generation so it is a homozygous for a particular trait .

For different traits are distributed to offspring independently of one another. For example, mental note is during all his work that the height of the plant and shape of two seeds the colour of Boss has no impact on one another.

The relationship of genotype and phenotype is not so simple so the dominant and recessive pattern described by Mendel dominance relations can be represented in the following for aspects complete dominance incomplete dominance and codominance over dominance.

complete dominance in this relation one allele is completely dominant Over The Other any tall TT is completely dominant dwarf tt.

Effect: in heterozygous condition Tt hides the dwarf character as seen in the pea plant.

in many cases the given allele does not completely mask the action of the second allele whether they interact in such a way that heterozygous phenotype is a mixing of both example in Mere bills alapa plant two types of flowers are present red and white as when crossed together the F1 hybrid appear pink that is intermediate between two variants.

discuss the different Allele of gene in are both are expressed in heterozygous condition 

any reason protein that stimulate the antibody formation is called antigen RBCs also carry some specific antigen that determine the type of blood group the important and the reason of blood are antigen a antigen B and antigen and antibodies these are the specific protein of the serum they are produced by the body in response to some for region protein are they are synthesized under the genetic control.

variation the difference of form size colour habits among the members of same species are known as variations sources following are the major sources of variation genetic recombination mutation environment.

sexual reproduction is responsible for breaking great diversity due to the following aspects independent assortment it is the random separation of chromosomes during Pro of game it gametes crossing over it is the exchange of parts between the non sister chromatids of homeo logos chromosomes it result in diversity of gametes mutation the spontaneous change in that changed the Jin products is called mutation it causes variations.

it is a cross between the heterozygous F1 offspring and the parent generation back cross the F1 hybrid may be crossed either with homozygous dominant or recessive parents test cross in a test cross the F1 hybrid are crossed with parents significance test cross is used to determine whether the individual exhibiting dominant character are homozygous or heterozygous.

The following is the difference between the phenotype and genotype phenotype it Express the character of an individual like form size colour behaviour it can be read out by direct observation same phenotype does not necessarily means the same genotype.

genotype it is the gene composition of an organism that determines characters it cannot be read out by direct observation. Individuals having the same genotype have the same phenotype.

It is also known as the product rule statement the probability that independent events occur simultaneously  is a product of their individual probabilities in mendelism cross between pea plants that are heterozygous for flower colour the probability of homozygous recessive offspring is calculated as follows.

Probability that an egg from F1 will receive a (P) allele ½.

Probability that a sperm will receive(P) allele1/2.

the overall probability at fertilization.

= 1/2 x ½

=¼

Probability that dominant allele will be in sperm and  recessive in egg

=1/2×1/2

=1/4

=1/2×1/2=¼

Therefore the probability that heterozygous offspring will be produced is.

when the phenotype expression of heterozygous (W*/W) Become more intense than the

Homozygous (W*/W)State of the dominant allele is called overdominance. For example, in fruit flies the heterozygous has more quantity of fluorescent pigment in eyes than the wild type.

It is a series of three more alternative allele forms of jeans only two of which can exist in any normal diploid individual. For example ABO blood group system is a good example of multiple alleles that were discovered by kari landsteiner stanier in 1901.

ABO system this blood group system is found in all humans types there are four principles of this system.

ABO system was explained by Bernstein in 1925 Abo blood group is a multiple allele trait that is encoded by a single polymorphic gene’ (I) on chromosome 9.Multiple allele are formed by mutation.

Ta

Gene      Ib

I

Dominance relation Ia Ib are completely dominant over I.

Ia and Ib are codominant to each other expression. These blood groups start expression in the early embryonic stage and or not changed throughout the life.

apart from a b o blood group system there exist some other antigen that are there were responsible for other blood groups there is blood groups are;

MSN

Lutheran

Kell

Lewis

Diego etc

Duffy

Kidd

it is the most important blood group system after ABO system.

name the name of this system was derived from rhesus monkey and the antigen for RH system was first observed in rhesus monkey .

antigen the antigen of RH blood system is the antigen D is present it is called Rh + otherwise RH negative

blood transfusion the RH factor have great role in blood transfusion and also in pregnancy when the mother is lacking the d antigen.

When mother is RH negative and foetus in RH positive the first RH pregnancy me not face much problems is very few of is very few of  foetus antigens cross the Placenta into maternal circulation  but when Placenta  detect at birth a large number of fetal cells enter the Mother’s bloodstream and stimulate antibodies treatment the mother is injected RH anti serum during early pregnancy and immediately after birth that prevent antibodies Pro in maternal blood

there is a rare blood group discovered by doctor . Y.M . Bhendi in 1952 .

Appearance in this blood group individuals are  phenotypically O  by genotypically A, B ,AB.

Reason the production of A,B  antigen is dependent on H’  substance if H substance is present in dominant form it can form A and B  antigen from there precursor otherwise the A, B are not expressed.

Percentage in Mumbai 0.01% local population can have this blood group. 

it is the phenomena in which the effect caused by the genes at one  locus interfere with the effect caused by another gene at another  locus

epistatic gene it is that mask the effect of action of a gene at another locus hypostatic gene it is the gene which is suppressed different from dominance epistasis epistasis is different from dominance because the dominance relationship in genes of same Loci will epistasis occur in gene occupying that different loci.

the inheritance of multiple allele is known as polygenic inheritance are the characteristic that is controlled by more than two genes is known as polygenic character have continuous distribution height skin colour it is this state are known as quantitative traits by increasing the number of genes controlling the trades the number of phenotype combinations also increase.

human skin colour is controlled by multiple genes.

Melanin  skin colour is largely determined by the amount of melanin in the skin that produces jeans at least three regions regulate the amount of melanin produced.

A  It is involved in the permanent survival producing melanocytes.

B  it is encoded in the enzyme tyrosinase involved in the production of melanin.

C  responsible for determining whether pheoMelanin Are melanin is produced forms dark and light Shades there are seven different shades of skin colour ranking from very light (aabbcc) to very dark (AABBCC).

The genes located in the same chromosome that tends to be inherited together are said to be linked genes and the phenomena of staying together is called  gene linkage.

autosomal linkage when the like the genes are present on autosomal chromosomes their linkage is known as autosomal linkage.

sex linkage when the linked genes are on 6 chromosomes this link it is called six linkage linkage group all the genes found on the same homologous pair  form a group called the linkage group

Number the number of linkage groups in an organism is equal to the number of  homologous pairs of chromosomes in that organism.

The genetic linkage can easily be detected by performing a test cross between the two gene pairs result linkage when all the four phenotype combination are produced in equal 1:1:1:1 so then there would be no linkage in complete linkage when more parental type and less Recombinant type  appeared this indicates the incomplete partial linkage.

Complete linkage when only parental types are produced complete of tight linkage is believed.

the experiment was performed by T.H Morgan on drosophila.

the wings shape:

normal ,  vestigial.

body colour:

grey and black.

cross when Morgan crossed between individuals having grey body and number wings with black body and vestigial wings the F1 inherited grey body and normal wings phenotypes.

test cross the result of test cross was following

grey body and normal wings

black body and vestigial wings

grey body and vestigial Wings

black body and normal wings

result it is concluded that most of Strings had a parent phenotype show the genes for body had colour and wing size are located on the same chromosomes however the small number of non parental phenotypes indicates that some mechanism occasionally break the linkage.

it is the proportion of Recombinant type between Tu Jine pairs as compared to the sum of all.

recombination frequency = Recombinant type/  sum of all  recombination x100

direct combination frequency between two linked genes can be calculated by crossing the heterozygous to homozygous recessive.

It is directly proportional to the distance between the linked gene loci.

it is also called genome mapping it is the creation of a genetic map assigning DNA fragments two chromosome when genome is first investigated this map is known existence some app improve with the scientific progress and is perfect when the genomic DNA Sequencing of the species is complete during the process the fragments are identified by small tags this may be genetic markers of DNA cutting enzymes.

the chromosomes that are responsible for determining the six of individual are called six chromosomes.

XX and XY chromosomes.

autosomes all chromosomes other than sex chromosomes are known as autosomes there is only one pair of six chromosomes in individual and the remaining are the autosomes.

it is a mechanism of six determination found grasshopper and protein or bugs.

Male: In this mechanism sex chromosome of male are XO’ It has only one x chromosome.

female XX Having to X 6 chromosomes.

sex determination vi determination depend upon male in this mechanism if the egg is fertilized with X chromosomes from male it result in female offspring otherwise male.

this type of six determination is found in the drosophila human and many other organism male in this mechanism male is XY  and produce two types of sperm having X or Y chromosomes.

female in this mechanism is XX  and produce a single type of egg having X chromosomes.

sex  determination vi determination in this mechanism depend on male is the sperm type X fertilized and the resulting embryo will be female and otherwise male.

sex ration  vi ratio between male and female offspring is 1:1.

it is a type of six determination mechanism found in birds butterflies and moths.

Discovery was discovered by j- seiler in 1914.

Male in this mechanism  the male is homozygous  having XX chromosomes in sperm.

females in this mechanism are heterozygous having two types of chromosomes the X or Y in egg.

Sex determination vi determination is dependent will cause on offspring of female.

Although  the basic mechanism of sex determination in drosophila and human in same the XX-XX  but there are still same differences.

XO:  absence of Y chromosome simply leads to the female development path turner’s syndrome in human produced through known this nondisjunction is a Sterile  female.

XXy:  in human XXy  produced through nondisjunction is a sterile male the klinefelter’s syndrome . but in drosophila fertile female.

who the transmission is associated with sex chromosomes are known as sex linked traits

reason the genes for these traits are present on X chromosome so they are inherited as sex linked traits.

haemophilia it is a sex linked disorder caused by a recessive gene present on X chromosomes colour blindness it is also a sex – ()  gene on X chromosome.

X linked recessive is a trait that is determined by on X linked recessive gene and its inheritance is known as X linked recessive inheritance carriers female having a single recessive gene are called carriers for the particular disorderNo symptoms of the disorder and have 50% on chances inheriting that disorder.

effects father affected father can only transfer the disorder through X chromosomes to his daughter and hot to his son example haemophilia colour blindness diabetes insipidus.

X linked dominant trait is determined by X linked dominant gene and its inheritance is called X linked dominant inheritance transmission all children of unaffected mother have 50% chances of disorder normal child of unaffected father can develop the disorder because only 5 chromosome from father is inherited to male child example alport syndrome.

(CLS)

idiopathic hypoparathyroidism

Vitamin D resistant rickets

in mammals the Y linked means when phenotypic trait  is determined by  allele on the Y chromosomes Y chromosome is small and does not contain many genes there for few trait r y linked and Y linked diseases are there delation:  the deletion of Y chromosome in male infertility on other example o Y linked inheritance is to be hairy ears.

[toggle title=”What are sex related and sex limited traits?

sex related traits are those which are at related with maleness are femaleness

control their traits may be controlled by sex-linked are antoSomal gene  sex limited traits their trade are confined to only one sex and Anatomical differences example gene for milk yield in Dairy cattle effect only cows.

beard growth in human is limited to man.

sex influenced traits are present in both males and females but they are more common in 16 control such traits are controlled by an allele that is expressed as the dominant in one but recessive in the other reason the difference in expression is due to hormonal difference between male and female example baldness it is inherited as an autosomal dominant trait it males but recessive in female a woman can be bald only when she is homozygous  recessive.