Practice free NEET NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
What is initiative substance of IAA? (PMT- 1990- APMEE 2002)
The initiative substance for Indole-3-acetic acid (IAA), which is a type of auxin, is Tryptophan. Tryptophan is an amino acid that serves as a precursor for the synthesis of IAA in plants.
What is apical dominance? (CPMT- 1989)
Apical dominance is a phenomenon in which the presence of the apical bud inhibits the growth of lateral (side) buds. This ensures that the plant grows taller rather than wider. The apical bud produces auxins, which suppress the growth of lateral buds, thereby promoting vertical growth.
Which of the following is water stress hormone? (CBSE-1993, MPPMT-1995, BHU 1998, CETCHD, Kerala 2000, Orissa- 2003)
Abscisic acid (ABA) is known as the water stress hormone. It plays a crucial role in helping plants respond to drought and other stress conditions by closing stomata to reduce water loss and promoting root growth to access more water.
If apical region of stem is removed from any plant, what is observed? (CMPT - 1993, CBSE -1994, 2000, KARNATAKA-2000)
When the apical region of a stem is removed, the suppression of lateral buds is lifted due to the reduced production of auxins. This results in the emergence of lateral branches, as the plant shifts its growth focus from vertical to lateral direction.
Which of the hormone is synthetic ? (MPPMT 1996, AIIMS 1996, BHU 1997, CPMT 1999)
2,4-D (2,4-Dichlorophenoxyacetic acid) is a synthetic auxin, a type of plant hormone. It is widely used as a herbicide to control broadleaf weeds.
What is 2-4 D ?
2,4-D is a common herbicide known as a weedicide. It is primarily used to eliminate unwanted broadleaf weeds in agriculture and other areas.
What is agent Orange ? (CBSE 1998, AIMS 1999)
Agent Orange is a herbicide and defoliant chemical. It is known for its use by the U.S. military as part of its herbicidal warfare program during the Vietnam War. It contains dioxin, which is harmful to both humans and the environment.
One plant group kept for 12 hrs in day and 12 hrs in night and flowering is observed in it. Another plant group is kept similarly for day - night period and for very short time light is given during dark period it do not flower. What is such type of plant called ? (CBSE 2004)
Short-day plants require long periods of darkness to initiate flowering. When a short light period is introduced during the dark period, it disrupts the critical dark period, preventing flowering. This is why the second group of plants did not flower when exposed to a brief light period during the dark phase.
How gibberrelin accelerates seed germination ? (AIIMS 2005)
Gibberellins promote seed germination by stimulating the synthesis of hydrolytic enzymes, such as amylase, that break down stored food reserves in the seed into simpler molecules. These simpler molecules are then used for the growth of the embryo, facilitating seed germination.
What is the colour of Phytochrome pigment ?
Ready to ace NEET?
Free access · No credit card required
Yes. You can attempt every NEET question on this page for free without logging in, and check the correct answer with a detailed explanation instantly.
No account is required to attempt questions and view answers. A free account adds bookmarks, personal notes, and progress tracking.
The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.