IMP Question For Board Examination | STD -12 | Chapter -2 | 2 Marks Theory Question

 

👉 NEET Biology Examination 

👉 NEET Biology Tips 

👉 NEET Biology Study Material

👉 UGC Net Study Material

Q1 . What is entomophily ? Describe the features of entomophilous flowers .

• It is a mode of cross pollination in which the pollen grains are transferred to the stigma through the insects like bees , butterflies , etc. Features of Entomophilous flowers The flowers are generally large , colourful , fragrant and rich in nectar . Pollen grains are often surrounded by a sticky substance , pollenkitt .

Q2 . What is the role of integuments of ovule after fertilization ? Which is the most common type of ovule found in angiosperms ? 

• The integuments of ovule get transformed into seed coats , outer testa and inner tegmen . Anatropous ovule

Q3 . What is double fertilisation ? Mention its significance . 

• Double fertilization is the joining of a female gametophyte with two male gametes .
• One sperm fertilizes the egg cell and the other sperm combines with the two polar nuclei of the large central cell of the embryo sac . This helps in providing enough nutrition to the embryo during seed germination .

Q4. Differentiate between albuminous and non - albuminous seeds , with an example for each

• Albuminous seed
• In some seeds , the endosperm persists as food storage tissue
• Example : Castor
• Non - albuminous seed
• If the endosperm is completely consumed by the developing embryo before seed maturation , the seeds are called non - albuminous .
• Example : Pea

Q5. Draw a vertical section of maize grain and label any three embryonic and three other parts .

Q6 . Draw a diagram of transverse section of an angiospermic anther . Label any six parts

Q7. Even though each pollen grain has two male gametes , why are at least 10 pollen grains and not 5 pollen grains required to fertilise 10 ovules present in a particular carpel

• A pollen tube carrying two male gametes , enter a ovule and release two male gametes which fuse with two different structures in a embryo sac ( the egg and two polar nuclei ) . Hence for fertilisation of 10 ovules , 10 pollen grains are required and not 5 pollen grains .

Q8 . If the chromosome number of a plant species is 20 , what would be the chromosome number in its ( 1 ) Pollen grains ( i ) Endosperm cells ?

• ( 1 ) Pollen grain = 10 ( i ) Endosperm cell = 30

Q9 . Banana is a true fruit and also a parthenocarpic fruit . Justify . 

• Since banana fruit is formed from the ovary , it is true fruit . It is parthenocarpic because the ovary develops into fruit without fertilisation

Q10 . Emasculation may not be necessary , yet bagging is necessary . Justify giving the condition when such a thing can happen .

• When the flower chosen is unisexual ( female ) , there is no need for emasculation . Yet bagging is necessary to prevent contamination of the stigma with unwanted pollen grains .

Q11 . If the chromosome number of plant species is 16 , what would be the chromosome number and the ploidy level of the ( 1 ) microspore mother cell and ( i ) the endosperm cells ?

• ( 1 ) Microspore mother cell = 16 ( Diploid ) ( it ) Endosperm cell - 24 ( Triploid )

Q12 . In the given figure of a typical dicot embryo , label the parts ( 1 ) , ( 2 ) and ( 3 ) . State the function of each of the labelled part .

• 1. Plumule forms the shoot
• 2. Cotyledons - Supply the food material
• 3. Radicle Grows into the root

Q13 . How does the study of different parts of a flower help in identifying wind as its pollinating agent ?

• The flowers are small , colourless , odourless and nectarless .
• Stigma is hairy and feathery .
• Pollen grains are light and non - sticky

Q14. State one advantage and one disadvantage of cleistogamy .

• Advantage : These flowers produce assured seed set even in the absence of pollinators .
• Disadvantage : Not advantageous to the plant since it does not result in genetic variation .

Q15 . Where is sporopollenin present in plants ? State its significance with reference to its chemical nature .

• The outer thick layer of pollen grain is called exine which is made up of sporopollenin .
• Biologically it is the most resistant substance so pollen grains are well preserved as fossils .

Q16 . Name the organic materials the exine and intine of an angiosperm pollen grains are made up of . Explain the role of exine .

• Exine is made up of sporopollenin and intine is made up of cellulose and pectin - Due to the sporopollenin , exine can withstand high temperature and strong acids . It is also not affected by enzymes . It is because of this reason that pollen grains are well preserved as fossils .

Q17 . Some angiosperm seeds are said to be ' albuminous ' whereas few others are said to have a perisperm . Explain each with the help of an example .

• In some seeds , the endosperm persists as food storage tissue . Such seeds are called albuminous seeds e.g. , castor . -
• In some seeds , residual nucellus persists which is called perisperm e.g. , Black pepper .

Q18 . List the two steps that are essential for carrying out artificial hybridization in crop plants and why ? 

• Emasculation and bagging are the steps in artificial hybridization .
• It is necessary to make sure that only desired pollen grains are used for pollination and the stigma is protected from contamination .

Q19 . List the post - fertilization events in angiosperms . 

• Development of endosperm
• Embryo formation 
• Seed formation
• Fruit formation

Q20 . Draw a labelled diagram of the sectional view of a mature pollen grain of angiosperms Explain the function of any two of its parts .

• Exine - It can withstand high temperature / strong acids . Intine - It is thin layer made up of cellulose and pectin .

========================================

Mail- indiabiologymanishmevada@gmail.com

Connect with this mail for more knowledge of Biology

This Site helpful for UGC Net Examination 

It is also helpful for MCAT (Medical College Admission Test) united States, Australia, Canada and caribbean islands.

For Join With Me Mail Me 

Manish Mevada

M.Sc, M.Phil, B.Ed

THANK YOU.