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Sexual Reproduction In Flowering Plants — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYSexual Reproduction In Flowering Plants4 Marks
Question
Write a short note on endosperm development.
✓

Answer

→ Endosperm development precedes embryo development.
→ The primary endosperm cell divides repeatedly and forms a triploid endosperm tissue.
→ The cells of this tissue are filled with reserve food materials and are used for the nutrition of the developing embryo.
→ In the most common type of endosperm development, the PEN undergoes successive nuclear divisions to give rise to free nuclei. This stage of endosperm development is called free-nuclear endosperm.
→ Subsequently cell wall formation occurs and the endosperm becomes cellular.
→ The number of free nuclei formed before cellularisation varies greatly.
→ The coconut water from tender coconut that you are familiar with, is nothing but free- nuclear endosperm (made up of thousands of nuclei) and the surrounding white kernel is the cellular endosperm.
→ Endosperm may either be completely consumed by the developing embryo (e.g., pea, groundnut, beans) before seed maturation or it may persist in the mature seed (e.g. castor and coconut) and be used up during seed germination.

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A regulatory body working under MoEF for the release of transgenic crop is ____________:
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A 23 year old Sahil has been diagnosed with an infection of reproductive tract caused by bacteria. He complains about burning sensation during urination, pus-containing discharge and pain around genitalia. This infection has incubation period of 2-5 days but can be cured.
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  3. Gonorrhoea.
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  1. Which among the following reproductive tract infections is transmitted by bacteria?
  1. Trichomoniasis.
  2. Chancroid.
  3. Genital warts.
  4. Both (a) and (b).
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  3. Use of antibiotic ampicillin.
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The process of translation requires transfer of genetic information from a polymer of nucleotides to synthesise a polymer of amino acids. The relationship between the sequence of amino acids in a polypeptide and nucleotide sequence of DNA or mRNA is called genetic code. George Gamow suggested that in order to code for all the 20 amino acids, code should be made up of three nucleotides.

  1. What is a codon?
  1. A length of DNA which codes for a particular protein.
  2. A part of the tRNA molecule to which a specific amino acid is attached.
  3. A part of the tRNA molecule which recognises the triplet code on the messenger RNA.
  4. A part of the messenger RNA molecule that has a sequence of bases coding for an amino acid.
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  1. 16
  2. 20
  3. 24
  4. 64
  1. Listed below are some amino acids and their corresponding mRNA triplets.
Amino acid
mRNA triplet
Phenylalanine
UUU
Lysine
AAG
Arginine
CGA
Alanine
GCA
Which DNA sequence would be needed to produce the following polypeptide sequence? Alanine-Arginine-Lysine-Phenylalanine

  1. $\text{CGT}\ \ \ \text{GCT}\ \ \ \text{TTC}\ \ \ \text{AAA}$

  2. $\text{CGT}\ \ \ \text{GCT}\ \ \ \text{TTC}\ \ \ \text{TTT}$

  3. $\text{CGU}\ \ \ \text{GCU}\ \ \ \text{UUC}\ \ \ \text{AAA}$

  4. $\text{CGU}\ \ \ \text{GCU}\ \ \ \text{UUC}\ \ \ \text{TTT}$

  1. Identify the non-sense codons among the following.
  1. AUG
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  1. A polypeptide is made using synthetic mRNA molecules as shown.
Synthetic mRNA used
Polypeptide produced
UUUAAAUUUAAA
Phenylalanine-Iysine-phenylalanine-Iysine

What are the DNA codes for the amino acids phenylalanine and lysine?

S.no
Phenylalanine
Lysine
(a)
AAA
TTT
(b)
AAA
UUU
(c)
GGG
CCC
(d)
TTT
GGG
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A young couple married for 5 years is unable to bear a child in spite of not practicing any birth control method. Upon consultation, doctor advised them an assisted reproductive technology involving transfer of gametes into oviducts.

  1. Identify the technique adopted by the couple.
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  1. What is the pre-requisite of this technique?
  1. Gamete formation should be normal.
  2. Fallopian tubes should be normal.
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  1. Assertion: GIFT is an in-vitro fertilisation technique.

Reason: In GIFT, gametes are fertilised outside the female body.

  1. Both assertion and reason are true, and reason is the correct explanation of assertion.
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  4. Both assertion and reason are false.
  1. The procedure advised to couple involves the transfer of:
  1. Fertilised ovum.
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  1. What is the success rate of this procedure?
  1. 30-50%
  2. < 20%
  3. 80-85%
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  1. The key benefits of the biopesticides are that they are:
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  1. Which of the following is used as an effective bacterial biopesticide?
  1. Trichoderma.
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  2. Aspergillosis
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  1. Both assertion and reason are true and reason is the correct explanation of assertion.
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Human male reproductive system comprises of a pair of testes, primary sex organs associated with formation of gametes and production of sex hormone. Study the given figure of human male reproductive system and answer the following questions.

  1. Which of the following is correct for labelled part P?
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  3. P is epididymis that carry sperms and secretion of seminal vesicles.
  4. P is rete testis, which lies along inner side of each testis and stores the sperms.
  1. Identify the correctly matched pair.
  1. Q - Vasa efferentia.
  2. R - Ejaculatory duct.
  3. S - Seminal vesicle.
  4. T - Cowper's gland.
  1. Which statement is incorrect for Q?
  1. It carries spermatozoa from epididymis to ejaculatory duct.
  2. Q are only 2 in number.
  3. It arises from rete testis.
  4. It constitutes male sex accessory duct.
  1. Which structure passes through the prostate gland and carries sperms and secretion of seminal vesicle?
  1. P.
  2. T.
  3. S.
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  1. Which of the following is not considered as microorganisms?
  1. Bacteriophage.
  2. Streptococcus.
  3. Porphyra.
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  3. Saccharomyces.
  4. Enterococcus.
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In today's world, more than 25% of human population is suffering from hunger and malnutrition. Scientists have developed techniques where microbes are grown on industrial scale as a source of good protein which can be grown from waste water, animal manure and even sewage. Single cell proteins are such products. TI1e biomass or protein is extracted from pure or mixed cultures of algae, yeasts, fungi or bacteria. These are a very good source of food for human consumption.

  1. Why the name single cell protein is applied?
  1. It contains only one type of protein.
  2. It is obtained from unicellular edible microbes.
  3. It contains only one type of microorganism.
  4. All of these.
  1. Which of the following is considered under single cell protein?
  1. Algae.
  2. Fungi.
  3. Cyanobacteria.
  4. All of these.
  1. Microorganisms can be a useful food resource for increasing human population because:
  1. These are easy to harvest.
  2. These can grow in water system.
  3. They have a high rate of multiplication thus producing huge biomass.
  4. They have high level of nucleic acid.
  1. Single cell protein can be grown from:
  1. Waste water.
  2. Animal manure.
  3. Sewage.
  4. All of these.
  1. Assertion: Production of single cell protein reduces pollution.

Reason: Single cell protein can be grown from waste water and even sewage.

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