What does the filiform apparatus do at the entrance into ovule?
It helps in the entry of pollen tube into a synergid
It prevents entry of more than one pollen tube into the embryo sac
It brings about opening of the pollen tube
It brings about opening of the pollen tube
A.
It helps in the entry of pollen tube into a synergid
In most cases, the mature embryo sac contains 7-cells and nuclei. The cells are arranged egg apparatus (two synergid cell and one egg cell,) a central cell with two nuclei and antipodal cells ( 3 in number). The synergid cells occur laterally to the egg cell. These cells are characterised by finger- like projections called filiform apparatus towards the micropylar end. Fill form apparatus is formed due to invaginations of cell wall into the protoplasm and is made up of pectocellulosic fibres evolved in the non-cellulosic sheath. Secretion of chemotactic substances for the attraction of pollen tube during fertilisation is the function of synergies. One synergid becomes degenerate during pollen entry into the embryo sac and thus, provides a way for the entry of pollen tube into the embryo sac.
Which one of the following condition in humans is correctly matched with tis chromosomal abnormality /linkage?
Klinefelter's syndrom-44 autosomes + XXX
Colourblindness- Y-linked
Erythroblastosis foetails - X-linked
Erythroblastosis foetails - X-linked
Which one of the following statement is incorrect about menstruation?
During normal menstruation, about 40 mL blood is lost
The menstrual fluid can easily clot
At menopause in a female, there is especially abrupt increase in gonadotropic hormones
At menopause in a female, there is especially abrupt increase in gonadotropic hormones
Consider the following statements concerning food chains
A) removal of 80% tigers from an area resulted in greatly increased growth of vegetation
B) removal of most of the carnivores resulted in an increased population of deers
C) length of food chains is generally limited to 3-4 trophic levels due to energy loss
D) the length of food chains may vary from 2 to 8 trophic level
Which two of the above statements are correct?
B and C
C and D
A and D
A and D
Which one of the following proved effective for biological control of nematodal diseases in plants?
Pisolithus tinctorius
Pseudomonas cepacin
Gliocladium virens
Gliocladium virens
Which one of the following is being tried in India as a biofuel substitute for fossil fuels
Jatropha
Azadirachta
Musa
Musa
Importance of day length in flowering of plants was first shown in
Lemna
tobacco
Cotton
Cotton
Haploids are more suitable for mutation studies than the diploids. This is because
Haploids are reproductively more stable than diploids
mutagens penetrate in haploids more effectively than is diploids
haploids are more abundant in nature than diploids
haploids are more abundant in nature than diploids
The linking of antibiotic resistance gene with the plasmid vector became possible with
DNA ligase
endonucleases
DNA polymerase
DNA polymerase
What is antissense technology?
A cell displaying a foreign antigen used for synthesis of antigens
Production of somaclonal variants in tissue cultures.
When a piece of RNA that is complementary to sequence is used to stop expression of a specific gene.
When a piece of RNA that is complementary to sequence is used to stop expression of a specific gene.
