Additive or Polymeric Genes

Comments

Post a Comment

Popular posts from this blog

Mushroom Cultivation

Image
A few important questions and answers for the students (1) What is spawn ?        Spawn is a fungal growth medium that already has mycelial fragments of mushroom which is used by the mushroom growers as inoculum. Fig. A packet of paddy straw mushroom spawn (2) What are the different types of spawn ? Mushroom spawns are of different types:- (i)  Natural spawn (ii) Milltrack spawn (iii) Brick spawn (iv) Flake spawn (vi) Tobacco spawn (vii) Grain spawn (3) Describe the method of spawning . Terrier (1945) first used wheat grain in spawning. Chang and Li, 1982 describe the following steps of grain spawning:- (i) Wheat grains are boiled first till it is half cooked, then water is drained off. (ii)To this 2% Calcium carbonate is mixed thoroughly. (iii) Then the mixture is transferred into glass tubes/ flasks. (iv)After plugging with non-absorbent cotton the mixture is autoclaved at 121°C for 30 minutes. (v) After cooling down to 30°C - 40°C , gr...
Read more

Plant Biotechnology and Tissue Culture

Image
1. What is "totipotency"?            The ability of a plant cell to perform all the activities of development like a zygote to develop into a complete plant is termed as totipotency. Haberlandt ,1902 first demonstrated totipotency by  in vitro technique. 2. How do haploid plants produced?       Haploid (n) plants are obtained by induction of embryogenesis during Anther and Pollen Culture.  3. How are   haploid plants made Homozygous diploid  ?                                          2/2020 BotH,TU   The chromosome set of haploid pollen grains are first doubled by mutagenic chemicals like colchine (0.5% for 24-48 hr.). Then homokaryotic fusion resulted into production of  homozygous diploid plants ( Vasil and Nitsch,1975). 4. What is Anther Culture?Describe the process with factors.      Th...
Read more

Fossil Plants

Image
Pentoxylon       Two stem genera (i) Pentoxylon sahnii and Nepanioxylon were discovered from Rajmahal hills, India. Morphology: (1) The stems of P.sahanii were 3 mm to 2 cm in cross section. (2) Rhomboidal leaf scars were present on the stem. (3) Leaves were arranged spirally. Leaves were described as Nipaniophyllum raoi. (4) Leaves simple, petiolate , margin entire, apex obtuse , 7cm long and 1 cm broad with a distinct single mid rib. (5) Reproductive organs were borne on short lateral shoots. Stem anatomy: (1) The stem was polystelic ( with 5 steles). (2) Each style was concentric with own cambium but in older stem secondary wood turned into excentric. (3) External to cambium was primary xylem and primary phloem. (4) Leaf traces were came off from long vascular strands. (5) There were 5 smaller strands alternating with the 5 main strands. (6) The secondary xylem was pycnoxylic - it is a coniferous character. (7) Leaf traces possessed centrifugal and centripe...
Read more