Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Syngamy
The pollen tube grows to a very limited extent in the synergid. It releases the contents either through a terminal or a subterminal pore. The contents include the two male gametes along with the accompanying cytoplasm, some reserve nutrients and perhaps vegetative nucleus. One of the sperms enters the egg and the other to the central cell. The distance that the male gamete has to travel to come in contact with the egg or secondary nucleus is insignificant. The male gamete comes in contact with the plasma membrane of the egg that forms a bridge through which the male gamete enters.
Nuclear fusion is initiated by the joining of the outer membrane of the two nuclei. The inner membrane also fuses at localized areas forming a small bridge between the two nuclei. Enlargement of bridge causes eventual fusion of the male and egg nuclei (syngamy). Depending upon the stage of the male gamete at the time of nuclear fusion, three types have been recognized. (a) in pre-mitotic type-the male nucleus fuses with the egg before reaching the mitotic inter phase, (b) in post-mitotic type the male nucleus undergoes inter phase while in contact with the egg and the fusion is postponed until the initiation of the first mitosis in both, and (c) in intermediate cases, the fusion occurs when male nucleus is still at interphase. Generally, the male cytoplasm does not take part in fertilization. However, there are plants in which biparental inheritance of plastids has been demonstrated.
Geotropism - Root and Shoot Morphogenesis Roots always grow towards gravity. The lot threshold of geotropic response requires as little time as one minute Gravity pulls auxin
Q. How different are animal cells from plant cells? While plant cells are eukaryotic, photosynthetic, autotrophic and have chloroplasts and cell wall, the animal cells are hete
Characteristics of Thin Gingiva Highly scalloped soft tissue and bony architecture Delicate friable soft tissue Minimal amount of attached gingiva Thin underlying
Ventricular Arrhythmias : These include premature ventricular contractions (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VT). At times they may be respon
What is Deuterostome. Explain in brief. Phyla, including the Chordata and Echinodermata which share common characteristics of blastopore-not forming the mouth, radial indetermi
State the term - Infection Infection is the invasion of the body by disease-producing (pathogenic) microorganisms and the reaction of the tissues to their presence and to the
Explain the term of measurement of height in veous pressure? Measurement of Height: Measurement of height of venous pressure is done from the sternal angle of Louis verticall
Q. What are the major parts of ferns? Ferns are constituted by small roots that come downwards from the rhizome stem and often horizontalized. The fronds also arise from the rh
What are the grasslands of North America and of South America respectively called? The steppe the grasslands of North America are called as prairies . The grasslands of South
Explain what is Class Osteichthyes ? Class Osteichthyes takes its name from the Greek root "osteo," referring to bone, and "ichthys," referring to fish. The bony fish have a sk
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd