Tag: botany

Questions Related to botany

In Mirabilis jalapa , the percentage of plants having pink and red flowers would be ________ when pink flower plant is test crossed.

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. 25% pink and 25% red

  2. 50% pink and 50% red

  3. 50% pink and 0% red

  4. 0% pink and 50% red

Show answer
Correct Option: B
Explanation:
 Gamete  R r 
 r Rr- Pink flower  rr- White flower 

Mirabilis jalapa is a plant showing incomplete dominance which means that when in F$ _1$ generation intermediate phenotype appears instead of the two parent phenotypes. 

While, the test cross is defined as a cross between an F$ _1$ plant and the homozygous recessive parent.
So, for plants to be pink in Mirabilis jalapa the plant has to be Rr in genotype. (where R is dominant on r while RR gives Red color and rr gives white color flowers in a plant).
Desired cross: Rr x rr 
So, the phenotype ratio is: 1:1::Pink flower:White flower
So, the correct answer is '50% pink and 50% red'.

Different forms of a gene are called

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. Heterozygotes

  2. Alleles

  3. Complementary genes

  4. Supplementary genes

Show answer
Correct Option: B
Explanation:

A.Heterozygotes – Organisms with a pairs of contrasting characters are called Heterozygotes.

B.Alleles - An alternative form of a character in a pair, controlled by a single gene is called Allele. It is dominant either in homozygous or heterozygous state.

C.Complementary gene – Two genes present on separate loci that interact together to produce a dominant phenotype is called Complementary gene. In the F2 generation 9:7 ratio.

D.Supplementary gene – genes which include two pairs of non-allelic genes. Both of them are involved in affecting the same character. Out of the non-allelic genes, one gene is dominant and can express by itself. Second gene is also dominant but expresses only when it is supported by the presence of the first gene. In the F2 geneartion 9:3:4 ratio.

So, the correct option is ‘Alleles’. 

A cross between yellow flowered and round fruit (both dominant) bearing plant and white flowered elongated fruit (both recessive) bearing plant yielded 20 plants in $F _1$ progeny which formed 960 plants in $F _2$ generation. The number of plants with yellow flowers and round fruits in $F _1$ and $F _2$ generations would be

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. 20, 960

  2. 20, 540

  3. 10, 180

  4. 10, 60.

Show answer
Correct Option: B
Explanation:

class=A cross is made between pure yellow flowered  and round fruit(YYRR) with white flowered elongated fruit(yyrr). In the F1 generation 20 progeny with yellow flowered and round fruits(YyRr) are formed. When they are subjected to self pollination followed by self fertilization, in the F2 generation, 960 progeny are formed. In these 540 plants are yellow flowered round fruits, plants are yellow flowered elongated fruits, 180 fruits are white flowered round fruits and 60 plants are white flowered elongated fruits the correct option is 20, 540

Two plants of Summer Squash both having circular fruits are crossed. $F _1$ plants had discoid fruits. $F _2$ generation has 3 types of fruits, discoid, circular and long in the ratio of

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. 9 : 3 : 4

  2. 9 : 6 : 1

  3. 12 : 3 : 1

  4. 7 : 6 : 3

Show answer
Correct Option: B

A modified dihybrid mendelian ratio of 9 : 3 : 4 indicates

botany classical genetics non mendelian inheritance deviation from mendelism genetics

  1. Supplementary genes

  2. Complementary genes

  3. Lethal genes

  4. Epistalic genes

Show answer
Correct Option: A
Explanation:

A.Supplementary genes – A pair of non allelic genes, one of which produces its effect independently in the dominant state while the dominant allele of the second gene is without any independent effect but is able to modify the effect of the former to produce to a new trait are called Supplemetary genes. Due to these genes in the F2 generation, 9:3:4 ratio of progeny are obtained. It is a modified Mendel dihybrid ratio.

B.Complementary genes – Two genes present on separate loci that interact

together to produce dominant phenotypic character; neither of them if present alone can express itself are called complementary genes. Due to these genes in the F2 generation, 9:7 ratio of progeny are obtained. It is a modified Mendel dihybrid ratio.

C.Lethal genes – A pair of genes present in the homozygous conditions, causes the death of the individual are called Lethal genes. Due to the genes, in F2 generation 2:1 ratio of progeny are obtained.

D.Epistatic genes – A gene which masks the action of another gene is termed as epistatic gene and process is called epistasis. Due to these genes in the F2 generation, either 9:3:4  or 12.3.1 ratio of progeny are obtained. It is a modified Mendel dihybrid ratio.

So, the correct option is ‘supplementary genes’.     

A cell weighing 1 mg grows to double its initial mass before dividing into two daughter cells of equal mass. Assuming no death, at the end of 100 divisions what will be the ratio of the mass of the entire populations of these cells to that of the mass of the Earth? Assume that mass of the Earth is $10^{24}Kg$ and $2^{10}$ is approximately equal to $1000$.

botany caskets of life the cell structure cytoplasm unicellular and multicellular organisms number and shape of cells diversity and classification in animals cell parameters

  1. $10^{-28}$

  2. $10^{-3}$

  3. $1$

  4. $10^3$

Show answer
Correct Option: D

Hybridoma cells are

cell parameters diversity and classification in animals number and shape of cells unicellular and multicellular organisms cytoplasm the cell structure caskets of life botany

  1. nervous cells of frog

  2. hybrid cells resulting from myeloma cells

  3. only cells having oncogenes

  4. product of spore formation in bacteria.

Show answer
Correct Option: B

Generally, gravitational water is utilized by the plants.

botany the leaf mechanism of absorption mineral absorption significance of transpiration

  1. True

  2. False

Show answer
Correct Option: B
Explanation:
Gravitational water is free water moving through soil by the force of gravity. It is largely found in the macropores of soil and very little gravitational water is available to plants as it drains rapidly down the water table in all except the most compact of soils.

So, the correct answer is 'False'.

Ion channels have been discovered by 

botany mineral nutrition in plants mechanism of absorption mineral absorption significance of transpiration

  1. Singer and Nicolson

  2. Garnier

  3. Robinson and Brown

  4. Neher and Sakmann.

Show answer
Correct Option: A

Activation energy is required for

botany mineral nutrition in plants mechanism of absorption mineral absorption significance of transpiration

  1. Exothermal reactions

  2. Endothermal reactions

  3. Enzyme mediated reactions

  4. Starting all biochemical reactions

Show answer
Correct Option: D
Explanation:

Activation energy is the minimum amount of energy required to initiate a chemical reaction.

So, the correct answer is 'Starting all biochemical reactions'.