Answer:The Cycad tree is the sporophyte.They have flagellated sperm.
Explanation:
During pollination, the contents of the megaspore divide to form many–celled gamateophyte called the endosperm and archegonium. There is a micropyle opening with a sticky fluid, which traps the wind-borne male gametophyte (microspores) which,at this time is made up of prothallus cell;an antheridial cell and a large tube cell. The trapped microspore is sucked into the archegonia chamber. Antherizoids are released, but only one penetrates each oospore and fuses with the female nucleus. The zygote is formed in the ovule and the later develops into seed.The diploid seed germinates into a new sporophyte plant and the life cycle begins again. Examples of cycad include Cycas circinalis ,Cycas celebrical and Cycas revoluta
Answer:
Answer : Depolarized
Explanation:
Sodium and Potassium ions tend to move inside of the axin when the membrane is depolarized.
A change in polarity occurs in the axon membrane when a nerve impulse travels across it. At the beginning of an action potential or nerve impulse , the ions of sodium tend to move inside of axon causing depolarization. As a result potassium ions tend to move outside of the axon causing re polarization. Hence, this effect causes the nerve impulse to travel in one direction only inside the axon.
Answer:
I believe the answer is d
Answer:
they are Na+, K+ and Ca2+ ion channels.
Explanation:
Ionotropic acetylcholine receptors are also called nicotinic acetylcholine receptors because beside acetylcholine (Ch) they respond to nicotine. These receptors are primary receptors in muscle for motor nerve-muscle communication that controls muscle contraction.
Two molecules of ACh are required for receptor to open. Since the receptors are linked to ion channels, the channels open. Opening of the channel allows positively charged ions to move across it: sodium enters the cell and potassium exits.
Answer:
The answer is actually B) Memory T. Memory T cells rapidly produce large numbers of effector T-cells when re-exposed to their antigens, which provides the immune system memory against past infections.
