Tag: biology

Hybridisation is defined as the process of interbreeding between two genetically divergent individuals or two individuals of different species. Therefore, the statement (i) is correct.
Interspecific hybridisation means cross mating between two different species but sharing same genera. For example, a cross breed between a lion and a tiger, they both are from same genus Panthera but different species. So the statement that cross between two varieties is called interspecific hybridisation is wrong.
I am a brinjal farmer, my brinjals are being infected by some beetles every year. I spend a huge sum of money on insecticides and pesticides to protect my crop. Then, a biotechnology company approaches me with a new strain or variety of brinjal plants which have the capability to produce a natural pesticide that makes it resistant to the beetles. My crop is not only saved, but  I also get good yield of brinjals now and earn a lot of money. I do not have to spend extra money on pesticides and insecticides. Basically, I got a brinjal plant with gene of desired character and got a desired genetically modified brinjal plants. Therefore, the statement (iii) is correct.
When the parent plants cross bred are from the same species, but of different variety is called intervarietal hybridisation. For example, a cross bred between two different varieties of wheat plant. They belong to the same species but they are of different variety. Therefore, the statement (iv) is wrong.
Hence, we can conclude that (i) and (iii) are correct statements.

The  method of altering the genetic pattern of plants to increase their value and utility for human welfare, is called crop improvement or plant breeding. It is a purposeful manipulation of plants to create desired plant types that are better suited for cultivation, give better yield and are disease resistant. iit is purely depends on domestication.

So the given statement is true.

The cochineal insect are introduced into the (Opuntia) prickly pear. The insect destroy the weeds without harming the crop plants. Its one of the biological method as well.

Yeast ferments the sugar present in the dough into carbon dioxide. The ${ CO } _{ 2 }$ released from the yeast fills the dough and increases its volume. Once, the bread has baked, the heat causes the bubbles to break and makes the bread light and fluffy.

• Triticale is a man-made crop developed by crossing wheat and cereal rye. It is probably the only new man-made crop in commercial production. 
• Triticale was found to be more efficient than wheat in utilizing and absorbing nitrogen from the soil. 
• It also produces a 30% higher yield on acid soils and is superior to wheat on copper-deficient soil.

• Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
• Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 

Pure breeding varieties are the one that carries same allele for a particular character and pass the trait without change from one generation to next upon selfing (for example, pure breeding tall (TT) plant carries two copies of “T” allele). Hybrids are the one which carries contrasting allele of a particular gene e.g., hybrid tall plant’s genotype is “Tt”. Incomplete dominance refers to the conditions where none of factors of a gene is dominant; the phenotype of heterozygous dominant individual is blend of dominant and recessive traits. Thus, it is an exception to Mendel’s principle of dominance. Heredity is genetic transmission of characters from parent generation to progeny. Alternative forms of a gene are called alleles e.g., alleles for gene for plant height are “T” and “t”. Thus, the correct answer is option A.

• Plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. 
• Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable characteristics for propagation, to more complex molecular techniques. 
• Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
• Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 
• Generally, a successful variety is one with a total balance of traits that makes it more profitable for growers. 
• Quality characters vary from one crop to another, e.g., grain size, colour, milling and baking qualities in wheat (Triticum aestivum), cooking quality in rice (Oryza sativa), malting quality in barley (Hordeum vulgare), size, colour, and flavour of fruits, keeping quality of vegetables, protein content in cereals and legumes, lysine content in cereals, methionine and tryptophan contents in pulses, etc.