Animal Kingdom Mnemonics 3
Examples: Pinctada, Sepia, Octopus, Dentalium, Aplysia, Chaetopleura, Pila, Loligo.
Animal Kingdom Mnemonics 2
PHYLUM ASCHELMINTHES/ NEMATODA:
Examples: Ancylostoma, Wuchereria, Ascaris, Rhabditis.
Animal Kingdom Mnemonics1
PHYLUM PORIFERA (SPONGES):
Examples: Spongilla, Euspongia, Sycon
Vernalization is the effect of cold temperature on flowering.
- It prevents precocious reproductive development late in the growing season and enables the plant to have sufficient time to reach maturity.
- These plants remain vegetative during the warm season, receive low temperature during winter, grow further & then bear flower & fruits.
- Lysenko 1st reported the effect of cold temperature on flowering in the wheat seedling.
Photoperiodism is the effect of light on flowering.
- Garner & Allard 1st reported the effect of light on flowering in Maryland Mammoth (variety of tobacco) & Glycine max.
On the basis of photoperiodic requirements, plants are divided into 3 types:
- Short day plants: in these plants, the dark period is very important for flowering. The dark period should exceed a critical length. Light has no effect on flowering. E.g., rice, sugarcane, potato, tobacco, soybean, Chrysanthemum.
- Long day plants: in these plants, the light period is very important for flowering. The light period should exceed a critical length. Darkness has an inhibitory effect on flowering. E.g., wheat, oat, spinach, radish, barley, lettuce.
- Day-neutral plants: these plants blossom throughout the year. Length of light or dark period has no effect. E.g., tomato, cucumber, sunflower, cotton, maize, pepper.
Abscisic acid (ABA) is a growth inhibitor.
- Discovered by 3 independent researchers as inhibitor-B, abscission II & dormin.They were chemically identical.
- Addicott isolated it from cotton balls. Later renamed as abscisic acid.
- Site of synthesis: chloroplast in leaves.
- Translocated through phloem.
- Formed by oxidation of carotenoids.
Ethylene is a volatile gaseous compound that stimulates transverse growth but retards longitudinal growth.
- Cousins confirmed its presence in ripened oranges, that hastened the ripening of stored unripe bananas.
- Formed in all parts of the plant i.e., roots, leaves, flowers, seeds.
- Maximum synthesis occurs in ripening fruits & tissues undergoing senescence.
- Synthesized from Methionine.
- Excess of auxin induces synthesis of ethylene.
- Biologically active at low concentration.