Genetics And Plant Breeding - Study Mode

[#321] The first intergeneric cross between bread wheat and rye was made by
Correct Answer

(C) Rimpau

Explanation

Solution: The first intergeneric cross between bread wheat and rye was made by Rimpau. The first 'true' allopolyploid triticale according to today's definition was bred in 1888 by the famous German plant breeder W. Rimpau who managed to create a cross between wheat and rye that was partially fertile. When crossing wheat and rye, wheat is used as the female parent and rye as the male parent (pollen donor). The resulting hybrid is sterile and must be treated with colchicine to induce polyploidy and thus the ability to reproduce itself.

[#322] Commercial hybrid seed production in cotton in our country has been possible due to which one of the following reasons
Correct Answer

(A) Availability of male sterile lines

Explanation

Solution: Commercial hybrid seed production in cotton in our country has been possible due to the availability of male sterile lines. In Cotton hybrid seed production is done either by conventional hand emasculation and pollination or by nonconventional (male sterility based). Genetic male sterility (GMS) in cotton occurs in a form of non-dehiscent anthers and unviable pollens when the reproductive development process fails due to possible loss of nuclear gene functions required for pollen development.

[#323] Consider the following crops 1. Bajra 2. Cotton 3. Maize 4. Rice Which one of the following is the correct sequence of the above crops according to the period of the development of first hybrid varieties in India?
Correct Answer

(B) 1, 3, 2 and 4

Explanation

Solution: Maize, Bajra, Cotton and Rice respectively are the correct sequence of the crops according to the period of the development of the first hybrid varieties in India. The first hybrid varieties in maize were released in 1961 when four hybrids, viz., Ganga 1, Ganga 101, Ranjit and Deccan, were released for cultivation. The first pearl millet hybrid HB 1 was released in 1965 thus making India the first country in the world to develop a grain hybrid utilizing cytoplasmic-genetic male-sterile line. Hirsutum, the first intraspecific hybrid was released in 1970 under the name H 4 from the Main Cotton Research Station, Surat of the Gujarat Agricultural University. Agricultural researchers at the Karjat Research Centre, Maharashtra, have developed the nation's first hybrid rice variety - krh-1 in 1994.

[#324] The actual pressure with which water enters into the cell is called?
Correct Answer

(A) DPD

Explanation

Solution: The actual pressure with which water enters into the cell is called DPD (Diffusion pressure Deficiet). DPD tends to equate and represents the water-absorbing ability of a cell, it is also called suction force (SF) or suction pressure (SP). The actual pressure with which a cell absorbs water is called "suction pressure". The cell membrane becomes stretched and the osmotic pressure (OP) of the cell decreases. As the cell absorbs more and more water its turgor pressure increases and osmotic pressure decreases.

[#325] Who gave the concept of circular chromosome in E. coli
Correct Answer

(A) Cairns

Explanation

Solution: The concept of circular chromosomes in E. coli is given by Cairns. John Cairns demonstrated the theta structure of E. coli chromosomal replication in 1963, using an innovative method to visualize DNA replication. The Escherichia coli chromosome is 4.6 Mb long, circular, and contains a single origin of replication. These characteristics present challenges for replication and segregation, which can nonetheless be completed as quickly as every 20 min.