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22701.

What is a choroid plexus? State its locations.

Answer»

Network of blood capillaries associated with the brain is called choroid plexus, which are anterior choroid plexus present on the roof of epithalamus and posterior choroid plexus located on the roof of medulla oblongata.

22702.

Distinguish between spinal nerve and cranial nerve.

Answer»
Spinal nerveCranial nerve
(i) They arise from spinal cord.(i) They arise from brain.
(ii) There are 31 pairs of spinal nerves(ii) There are 12 pairs of cranial nerves.

22703.

Name the region consisting of nerve fibres that connects cerebrum and medulla oblongata.

Answer»

Pons Varolii.

22704.

What is EEG?

Answer»

EEG is electro encephalography. It is used to detect the electrical changes taking place in the brain.

22705.

Give the names of cranial nerve number VIth and VIIth.

Answer»

VTth cranial nerve is Abducens and Vllth cranial nerve is Facial.

22706.

What is the difference in ‘tract’ and ‘nerve’?

Answer»

A bundle of axons within CNS is called a ‘tract’ while the one outside the CNS is called ‘nerve’.

22707.

Name the band of nerve fibres that connect cerebrum, cerebellum and spinal cord.

Answer»

Crura cerebri.

22708.

Mention the major sulci present in the cerebral hemispheres.

Answer»

The sulci present in the cerebral hemisphere are – central sulcus, parieto-occipital sulcus and lateral sulcus.

22709.

Name the site where actual exchange of O2 and CO2 takes place between air and blood in the body of man.

Answer»

Alveolus of lung.

22710.

Name the three sulci present on the cerebral hemispheres.

Answer»

Central sulcus, lateral sulcus and parieto¬occipital sulcus.

22711.

Where are lateral ventricles situated and what is its roof called?

Answer»

Lateral ventricles are the cavities filled with cerebrospinal fluid, present inside the cerebrum and its roof is called pallium.

22712.

………………. is the largest commissure of the human brain. (a) Corpora striata (b) Corpora quadrigemina (c) Habencular commissure (d) Corpus callosum

Answer»

Correct answer is (d) Corpus callosum

22713.

Sweat glands are – (a) Apocrine (b) Merocrine (c) Acrine (d) None of the above

Answer»

The answer is (c) Acrine
 

22714.

Sebaceous glands are –(a) Apocrine (b) Mesocrine (c) Holocrine (d) Acrine

Answer»

The answer is (c) Holocrine

22715.

Melanin pigments in the hair are found in – (a) Cortex (b) Cuticle (c) Medulla (d) All of the above

Answer»

The answer is (a) Cortex

22716.

A barrier layer of the skin is stratum – (a) corneum (b) Ludum (c) granules (d) spins

Answer»

The answer is (b) Ludum

22717.

Which vitamin is synthesized in the skin?

Answer»

The answer is Vitamin D.

22718.

Which pigment imparts color to the skin?

Answer»

The answer is Melanin pigment.

22719.

Why skin is called “Jack of all trades”?

Answer»

The skin performs almost all the body functions. Hence, they are called “Jack of all trades”.

22720.

Who promises to pay for the Two Blind Men’s dinner?(a) The Donkey Driver(b) Pierre(c) The Innkeeper(d) The Comedian

Answer»

(d) The Comedian

22721.

Where were the two blind men begging?(a) At the “The Green Dragon’(b) Outside the city gate(c) Inside a stable(d) At a public square

Answer»

(b) Outside the city gate

22722.

Describe human mammary glands.

Answer»

Mammary glands: 

  • In Prototheria, human beings and other primates, the mammary glands are modified apocrine sweat glands. In remaining mammals, they are modified compound alveolar sebaceous glands. 
  • Each mammary gland has a teat through which the mammary gland opens out. The area around the teat is darkly pigmented which is called as areola mammary. 
  • The mammary glands secrete the milk. The milk contains mainly carcinogen, lactoglobulin, lactoalbumin, lactose and fats. In human beings, there is a pair of mammary glands on the thorax.
22723.

Where does the Comedian put the donkey?विदूषक गधे को कहाँ रखता है?

Answer»

The Comedian puts the donkey into the stable of the Innkeeper.

विदूषक गधे को सराय मालिक की घुड़शाला में रखता है।

22724.

The Innkeeper says, “Rest assured that I’ll take good care of him” whom does “him” refer here?(a) The Donkey Driver(b) The First Blind Man(c) The Donkey(d) The Comedian

Answer»

(c) The Donkey

22725.

To whom does the comedian say: “And I thank you for your kind treatment.”(a) The First Blind Man.(b) The Second Blind Man(c) The Donkey Driver(d) The Innkeeper

Answer»

(c) The Donkey Driver

22726.

Whom does the First Blind Man call “filthy beggar”?(a) The Second Blind Man(b) The Donkey Driver(c) The Comedian(d) The Innkeeper

Answer»

(c) The Comedian

22727.

Which of the following is a totally impossible outcome of Mendel’s Experiment (cross breeding pure bred tall and short pea plants) (a) 3 tall 1 short plant (b) 24 tall and 8 short plants (c) 8 tall and 0 short plants (d) 4 tall plants and 1 medium-height plant.

Answer»

(d) 4 tall plants and 1 medium-height plant.

22728.

List any two contrasting characters other than height that Mendel used in his experiments in pea plants.

Answer»

The two contrasting traits other than height used by Mendel are :

(i) Pod colour - Green pod colour dominant over yellow colour

(ii) Seed shape - Round seed shape dominant over wrinkled seed shape.

22729.

Comment upon the appropriateness of the title of the play.एकांकी के शीर्षक की उपयुक्तता पर टिप्पणी कीजिए।

Answer»

The title of the play is ‘Two Blind Men and a Donkey’. The whole story revolves around these two men and the beast. The donkey is the medium. If donkey is removed from the story similarly the Two Blind Men, there remains null in the story. Thus the title is appropriate and appreciable.

एकांकी का शीर्षक ‘दो अंधे व्यक्ति और एक गधा’ है। सम्पूर्ण कहानी इन दोनों व्यक्तियों और जानवर के इर्द-गिर्द घूमती है। गधा इसमें माध्यम है। यदि कहानी से गधे को हटा दिया जाए या उसी तरह से दोनों अंधे व्यक्तियों को, कहानी में कुछ भी नहीं शेष रहता है। इस प्रकार से यह शीर्षक उचित एवं प्रशंसनीय है।

22730.

Point out two instances of dramatic irony in the play.एकांकी में आए हुए दो नाटकीय व्यंग्य के उदाहरण दीजिए।

Answer»

The first dramatic irony occurs when the donkey arrives and licks the hands of two blind men. They think that it is a generous lady. The reality comes when the donkey brays. The second occurs when it is the turn of the payment of the bill. Each one thinks that the other has the ducat.

प्रथम नाटकीय व्यंग्य उस समय का है जब गधा आता है और उनका हाथ चाटता है। वे सोचते हैं कि यह कोई उदार महिला है। वास्तविकता तब आती है जब गधा रेंकता है। दूसरा व्यंग्य तब घटित होता है जब बिल के भुगतान का समय आता है। प्रत्येक यह सोचता है कि स्वर्ण मुद्रा दूसरे के पास है।

22731.

Do you agree that the play would not have been possible without the Comedian? Give reasons for your answer.क्या आप सहमत हैं कि बिना विदूषक के यह एकांकी सम्भव नहीं है? अपने उत्तर में तर्क दीजिए।

Answer»

The Comedian is a major character in the play. The incidents in this play revolves around him. The main role of the Comedian is to amuse people. The Comedians have top position in the society at the time. I think the Comedian is necessary in this story. The absence of this character may give a different turn to the story. It is the Comedian who watches that the two Blind Men are cheated. He promises the Innkeeper that his bill will be paid.

The Comedian talks cleverly to the Innkeeper and takes the donkey to the stable of the Innkeeper. It is the Comedian who tells the donkey driver that he is transformed into an ass and again into a human being. The Comedian teaches a lesson to the donkey driver that he has mocked poor and has faced the punishment. He warns him not to do so with the others. These events relate us that the Comedian is present at all the important places in the story. He is the cause of the climax as well as the end of the story.

एकांकी में विदूषक एक बड़े पात्र के रूप में है। एकांकी की घटनाएँ उसके चारों ओर घूमती हैं। विदूषक का मुख्य कार्य लोगों को आनन्दित करना है। समाज में उस समय विदूषकों को उच्च स्थिति प्राप्त है। मैं सोचता हूँ कि इस कहानी में विदूषक अनिवार्य है। इस पात्र की अनुपस्थिति इस कहानी को भिन्न रूप प्रदान कर सकती है। यह विदूषक ही है जो यह निगरानी करता है कि दोनों अंधे व्यक्तियों को धोखा दिया गया है। वह सराय मालिक से वादा करता है कि उसके भोजन के बिल का भुगतान हो जाएगा।

विदूषक सराय मालिक से चतुरता से बात करता है और सराय मालिक की घुड़शाला में गधा ले जाता है। यह विदूषक ही है जो गधा चालक को कहता है कि वह एक गधे में बदल गया है और वापस एक मानव में बदल गया है। विदूषक गधा चालक को एक पाठ सिखाता है कि उसने गरीब का मजाक उड़ाया है और वह दण्ड भुगत चुका है। वह उसे चेतावनी देता है कि दूसरों के साथ इस प्रकार से नहीं करें । घटनाएँ हमें यह बताती हैं कि सभी महत्त्वपूर्ण स्थानों पर कहानी में वह उपस्थित है। वह कहानी के उत्थान और अन्त का कारण है।

22732.

Discuss the central theme of the play.एकांकी की मुख्य विषय-वस्तु पर चर्चा कीजिए।

Answer»

The story of the play is interesting, amusing and awakens curiosity at certain places. It is written in a very simple and lucid manner. The story is about the two blind men who are beggars. These people amuse due to their follies they do due to blindness. They consider an animal as a generous lady. Later the braying of donkey let them know that it was the donkey. In this story the writer draws the attention, never to mock a poor and helpless man. The Donkey Driver is taught a lesson with the help of the comedian.

On the other hand the comedian does the works full of help to those who are in trouble and kindness towards helpless people. The two Blind beggars fail to pay their bill for the dinner at the Green Dragon. They are cheated by the donkey driver. When the Innkeeper scolds them and threatens to hand over them to police. The comedian helps them. He gives the donkey of Donkey Driver to the Innkeeper to adjust donkey for payment of dinner. The Donkey driver has to pay double in a sense. He loses the donkey as well as gives money to the comedian also. Though it is in religious sense or some other manner.

एकांकी की कहानी रुचिकर, आनन्ददायक और कुछ स्थानों पर जिज्ञासा जगाने वाली है। यह बहुत सरल और बोधगम्य तरीके से लिखी गई है। यह कहानी दो अंधे व्यक्तियों के बारे में है जो भिखारी हैं। यह लोग अपने अंधेपन के कारण की गई मूर्खताओं से लोगों को आनन्दित करते हैं। वह एक जानवर को उदार महिला समझते हैं। बाद में गधे का रेंकना उन्हें यह बताता है कि यह गधा था। इस कहानी में लेखक ध्यान आकर्षित करता है कि कभी भी किसी गरीब और असहाय का मजाक नहीं उड़ाना चाहिए। गधा चालक को विदूषक के द्वारा एक पाठ पढ़ाया जाता है।

दूसरी ओर विदूषक वह कार्य करता है जिसमें समस्याग्रस्त लोगों की सहायता और असहाय लोगों के प्रति दयालुता होती है। द ग्रीन ड्रेगन पर दोनों अंधे भिखारी अपने भोजन का बिल नहीं चुका पाते हैं। वे गधा चालक द्वारा ठगे जाते हैं। जब सराय मालिक उन्हें फटकारता है और पुलिस को सुपुर्द करने की धमकी देता है, विदूषक उनकी सहायता करता है। वह गधा चालक को गधा सराय मालिक को भोजन के भुगतान के रूप में समायोजित करने को देता है। गधा चालक को एक प्रकार से दुगुना भुगतान करना पड़ता है। वह गधा भी खो देता है और विदूषक को पैसे भी दे देता है। यद्यपि यह धार्मिक भावना या कोई अन्य रूप है।

22733.

Who speaks the following words to whom and why? “It is nothing. Only a habit of my donkey life. I shall have some difficulty in getting rid of it. But in time, it will pass.”निम्न शब्द कौन किसे कहता है और क्यों?”यह कुछ भी नहीं है केवल मेरे गर्दभ जीवन की आदत है। इससे छुटकारा पाने में मुझे थोड़ी परेशानी होगी, परन्तु समय रहते यह गुजर जाएगी।”

Answer»

The Comedian speaks these words to the Donkey Driver because the Comedian acts as a donkey. He relates the Donkey Driver his story how he is transformed into an ass and then again as a man. In order to prove the Donkey Driver that the habit still remains with him, the Comedian imitates the donkey’s bray and explains him in these words.

विदूषक इन शब्दों को गधा चालक से कहता है क्योंकि विदूषक एक गधे की भाँति कार्य करता है। वह गधा चालक से अपनी कहानी कहता है। वह कैसे गधा बना और फिर वापस एक आदमी। गधा चालक को यह साबित करने के लिए कि यह आदत उसकी अभी तक बनी हुई है, विदूषक गधे के रेंकने की नकल करता है और उसे इन शब्दों में व्यक्त करती है।

22734.

What trick does the Comedian play upon the Donkey Driver?गधा चालक पर विदूषक क्या चाल चलता है?

Answer»

The Comedian gives Donkey Driver’s donkey to the Innkeeper. He puts himself into the halter in place of donkey. When Donkey Driver comes to take his donkey the Comedian tells him that he is his donkey who has transformed into a human being again. The Donkey Driver gives him some money and exists.

विदूषक गधा चालक का गधा सराय मालिक को दे देता है। वह गधे के स्थान पर अपने आपको रस्से में बाँध लेता है। जब गधा चालक अपना गधा लेने आता है, विदूषक उससे कहता है कि उसका गधा मानव रूप में बदल गया है। गधा चालक उसे कुछ पैसे देता है और वहां से विदा हो जाता है।

22735.

Explain the following passage with reference to the contextनिम्न पद्यांश की सन्दर्भ सहित व्याख्या करेंThis donkey driver has won my full admiration, and now, ladies and gentlemen, with your kind permission, I shall make him the hero of a farce of my own.

Answer»

Reference to the context – These lines have been taken from the famous playwright Mathurin Dondo’s one-act comedy entitled as “Two Blind Men and a Donkey”. These lines are spoken by the comedian. He addresses to the public sitting before him. Comedian relates here to the audiences the forthcoming story to arouse the curiosity of the spectators.

Explanation – The comedian tells the audiences that he himself makes people laugh with his acts. He has visited many places as he is a wandering comedian. In the knowledge of the comedian what the donkey driver has tricked on two blind men, such an act of merry making has never been played. The comedian decides in these lines that the donkey driver will be made a hero of his own farce. He will also tell his wits. Donkey driver is admired in these lines.

The lines make the audiences curious and it is also an indication of the turn of the story. This is a kind of preparation on the part of the playwright that they should accept pleasurely what comes next. Critical Commentary – The playwright speaks through the mouth of the comedian in these lines. These simple lines tell us that something new and exciting is going to be played. This is a nice technique to keep the audiences active.

सन्दर्भ एवं प्रसंग – यह पंक्तियाँ प्रसिद्ध नाटककार मथुरिन डोन्डो की एकांकी जिसका शीर्षक ‘दो अंधे व्यक्ति और एक गधा’ से ली गयी हैं। यह पंक्तियाँ विदूषक के द्वारा बोली गई हैं। वह अपने सामने बैठी जनता को सम्बोधित करता है। विदूषक यहाँ पर श्रोताओं को आगे की कहानी कहता है जिससे कि दर्शकों में जिज्ञासा पैदा हो। व्याख्या – विदूषक श्रोताओं को कहता है कि वह स्वयं अपने कार्यों से लोगों को हँसाता है। उसने कई स्थानों का भ्रमण किया है क्योंकि वह एक घूमता हुआ विदूषक है।

विदूषक के ज्ञान में जो चालाकी गधा। चालक ने दोनों अंधे व्यक्तियों पर की है, इस प्रकार की आनन्द करने वाली बात कभी नहीं की गई है। विदूषक इन पंक्तियों में यह निर्णय करता है कि उसके हास्य का नायक गधा चालक को बनाया। जाएगा। वह उसकी बुद्धि का परीक्षण भी करेगा। गधा चालक की इन पंक्तियों में प्रशंसा की गई है। यह पंक्तियाँ श्रोताओं को उत्सुक बनाती हैं और यह कहानी में मोड़ लेने का संकेत है। नाटककार की ओर से यह एक तैयारी है कि जो कुछ आने वाला है वे उसे प्रसन्नता से स्वीकार करें। आलोचनात्मक टिप्पणी-इन पंक्तियों में नाटककार यहाँ पर विदूषक के मुँह से बोलता है। यह सरल पंक्तियाँ हमें कहती हैं कि कुछ नवीन और उत्तेजना करने वाला होगा। यह श्रोताओं को सक्रिय करने की एक नवीन तकनीक है।

22736.

Do you think the donkey driver really deserved his comeuppance? Justify your answer.क्या आप मानते हैं कि गधा चालक वास्तव में दण्ड के योग्य है? अपने उत्तर की तर्कसंगतता को स्पष्ट कीजिए।

Answer»

Donkey driver is the chief figure in the story of the play. His acts are also amusing and interesting. He is also a God fearing man. When the Two Blind men ask him to pity on them, he tells them that he will reward them a ducat. He turns from them without giving anything. Both the blind men are hungry. They turn towards the Green Dragon for dinner. At the time of payment they have nothing. Donkey driver is there to enjoy their bad condition. He is smiling and amusing himself. It is an unkind and inhuman act on his part. He needs to be punished for this act.

When the donkey driver comes to know that his donkey is a human being, actually it is not so. The Comedian becomes his ass. He expresses sorrow for his ill-treatment. He tells the Comedian that he never knows that his donkey is a human. If the donkey tells him that he is a human being he will not treat him ill. This is good on his part. But the donkey driver treats his beast in a bad manner, it is bad on his part. His behaviour with two blind men is also bad so he deserves what the Comedian has done.

एकांकी की कहानी में गधा चालक एक मुख्य पात्र है। उसके कार्य भी रुचिकर और आनन्द प्रदान करने वाले हैं। वह भगवान से डरने वाला व्यक्ति है। जब दोनों अंधे व्यक्ति अपने पर दया करके उससे कुछ माँगते हैं, वह उनसे कहता है कि वह उनको एक स्वर्ण मुद्रा उपहार में देगा। वह उन्हें बिना कुछ दिये वहाँ से मुड़ जाता है। दोनों अंधे व्यक्ति भूखे हैं। वे द ग्रीन ड्रेगन सराय में भोजन हेतु जाते हैं। भुगतान के समय उनके पास कुछ भी नहीं है। गधा चालक उनकी दुर्दशा का आनन्द लेने वहाँ पर है। वह स्वयं मुस्कुराकर आनन्दित हो रहा है। यह उसकी ओर से अद्यालुता और अमानवीयता का कार्य था।

उसे इस कार्य हेतु दण्डित किया जाना चाहिए। जब गधा चालक को यह पता चलता है कि गधा एक मानव है, वास्तव में ऐसा नहीं है। विदूषक उसका गधा बनता है। वह अपने दुर्व्यवहार के लिए दुःख व्यक्त करता है। वह विदूषक से कहता है कि वह यह कभी नहीं जान पाया कि उसका गधा मानव है। यदि गधा उससे कहता कि वह मानव है, वह उससे दुर्व्यवहार नहीं करता। यह उसकी ओर से अच्छा है। परन्तु गधा चालक अपने जानवर के साथ दुर्व्यवहार करता है। यह उसकी ओर से गलत है। उसका दो अंधे लोगों के साथ व्यवहार गलत है इसलिए जो विदूषक ने किया वह उसके योग्य है।

22737.

If we cross-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant, we will get plants of F1 generation. If we now self-cross the pea plant of F1 generation, we obtain pea plants of F2 generation.(i) What do the plants of F1 generation look like ? (ii) State the ratio of tall plant to dwarf plants in F2 generation.(iii) State the type of plants not found in F1 generation but appeared in F2 generation Write the reason for the same.

Answer»

(i) Tall

(ii) 3: 1

(iii) Dwarf

Reason: Being a recessive trait, dwarfness can only be expressed in the absence of a dominant trait/ in its pure form.

22738.

A cross was carried out between a pure bred tall pea plant and a pure bred dwarf pea plant and F1 progeny was obtained.Later, the F1 progeny was selfed to obtain F2 progeny. Answer the following questions : (i) What is the phenotype of the F1 progeny and why ? (ii) Give the phenotypic ratio of the F2 progeny. (iii) Why is the F2 progeny different from the F1 progeny ?

Answer»

(i) The phenotype of F1 progeny is Tt because F1 or hybrid plants were not intermediate between the two alternate forms of a character. They resembled only one parent. In a cross between tall and dwarf of pea plants, the F1 plants were all tall. 

(ii) The phenotypic ratio of F2 progeny is 3: 1. 

(iii) F1 progeny resembled only one parent which is dominant in nature but in F2 progeny phenotypically three plants are tall and one plant is dwarf. But according to genotype ratio, one plant is pure tall, two are hybrid tall and one plant is a pure dwarf.

22739.

A section of DNA providing information for one protein is called— (a) Nucleus (b) Chromosomes (c) Trait (d) Gene

Answer»

A section of DNA providing information for one protein is called  Gene.

22740.

What happens when the animal licks the hands of the two Blind men ?जब जानवर दोनों अंधे व्यक्तियों के हाथ को चाटता है तो क्या होता है?

Answer»

The animal is a donkey. The two blind men consider the animal as a human. They request in their most polite manner for alms. They show that they are very poor. The animal licks their extended hands. Both the men take it as a lady. They are sure to get something. There is no word from the other side. The blind men are surprised. After sometime the animal goes away. They come to know about the animal when it brays. They also discuss what animal it is.

जानवर गधा है। दोनों अंधे व्यक्ति उसे एक इंसान मानते हैं। वे अपने सबसे विनम्रतम तरीके से भिक्षा मांगते हैं। वे यह दिखाते हैं कि वे बहुत गरीब हैं। जानवर उनके बढ़े हुए हाथों को चाटता है। दोनों आदमी उसे महिला के रूप में मानते हैं। उन्हें यह विश्वास है कि वे कुछ अवश्य पाएंगे। दूसरी ओर से कोई शब्द नहीं आता है। दोनों अंधे व्यक्ति आश्चर्यचकित होते हैं। उनको तब पता चलता है जब जानवर रेंकता है। उन्होंने यह भी चर्चा की है कि यह कौनसा जानवर है।

22741.

What happens when the animal licks the hands of the two Blind men ?जब जानवर दोनों अंधे व्यक्तियों के हाथ को चाटता है तो क्या होता है?

Answer»

The animal is a donkey. The two blind men consider the animal as a human. They request in their most polite manner for alms. They show that they are very poor. The animal licks their extended hands. Both the men take it as a lady. They are sure to get something. There is no word from the other side. The blind men are surprised. After sometime the animal goes away. They come to know about the animal when it brays. They also discuss what animal it is.

जानवर गधा है। दोनों अंधे व्यक्ति उसे एक इंसान मानते हैं। वे अपने सबसे विनम्रतम तरीके से भिक्षा मांगते हैं। वे यह दिखाते हैं कि वे बहुत गरीब हैं। जानवर उनके बढ़े हुए हाथों को चाटता है। दोनों आदमी उसे महिला के रूप में मानते हैं। उन्हें यह विश्वास है कि वे कुछ अवश्य पाएंगे। दूसरी ओर से कोई शब्द नहीं आता है। दोनों अंधे व्यक्ति आश्चर्यचकित होते हैं। उनको तब पता चलता है जब जानवर रेंकता है। उन्होंने यह भी चर्चा की है कि यह कौनसा जानवर है।

22742.

Which one is a possible progeny in F2 generation of pure bred tall plant with round seed and short plant with wrinkled seeds? (a) Tall plant with round seeds (b) Tall plant with wrinkled seeds (c) Short plant with round seed (d) All of the above

Answer»

 (d) All of the above

22743.

Explain why xylem transport is unidirectional and phloem transport bidirectional.

Answer»

Food, primarily sucrose, is transported by the vascular tissue phloem from a source to a sink. Usually, the source is understood to be that part of the plant which synthesizes the food and sink, the part that needs or stores the food. But, the source and sink may be reversed depending on the plant’s needs. Sugar stored in roots may be mobilised to become a source of food in the early spring when the buds of trees, act as sink; they need energy for growth and development of the photosynthetic apparatus. Since the source-sink relationship is variable, the direction of movement in the phloem can be bi-directional. This contrasts with that of the xylem where the movement is always unidirectional.

22744.

Explain why xylem transport is unidirectional and phloem transport bi-directional.

Answer»

Water transported through xylem is utilised in photosynthesis and most of the water is lost through transpiration. Renewed demand for water is once again supplied through the same channel. Hence, transport through xylem is unidirectional. In case of phloem transport, food is transported from source to sink. Leaves are the usual source and storage organs are the usual sink. But the storage organs become source when new buds emerge during early spring. In that case, a reverse flow of food is required. Hence, movement through phloem is bi-directional. 

22745.

What essential role does the root endodermis play during mineral absorption in plants?

Answer»

Minerals need to be actively absorbed by the epidermal cells. Specific proteins in the membranes of root hairs actively pump ions from the soil to the epidermal cells. 

22746.

What are the Uptake and transport of mineral nutrients?

Answer»

Ions are absorbed by the roots by passive and active transport. The active uptake of ions require ATP energy. Specific proteins in membranes of root hair cells actively pump ions from the soil into the cytoplasm of epidermal cells and then xylem. The further transport of ions to all parts of the plant is carried through the transpiration stream.

22747.

Briefly describe two pathways through which mineral nutrients absorbed by roots are carried to the xylem.

Answer»

Apoplast pathway : The ions enter the cell wall of epidermis and move across the cell wall from epidermis to xylem and finally gets accumulated there. 

Symplast pathway: The ions enter the cytoplasm of epidermis and move across the cytoplasm of epidermis to cytoplasm of pericycle through phasmodesmata and finally to xylem vessels.

22748.

Name the pathways by which water flows from roots hair to the deeper layers of root.

Answer»

Apoplast pathway and symplast pathway.

22749.

Classify the following to form Column B as per the category given in Column A.i. Alternaria crassaii. Agrobacterium spp. iii. Cactoblastis cactorum iv. Beavueria bassianaColumn A (Biocontrol agents)Column B (Host)Microbial pesticide————Mycoherbicide————Insect as herbicide————Bacterial herbicide————

Answer»
Column A (Biocontrol agents)Column B (Host)
Microbial pesticideBeavueria bassiana
MycoherbicideAlternaria crassa
Insect as herbicideCactoblastis cactorum
Bacterial herbicideAgrobacterium spp.
22750.

What is the role of Ca and ATP in muscle contraction?  OR What is the role of calcium ions in muscle contraction? OR Trace the events in a muscle fibre from the time it receives the impulse through the neuromuscular junction up to the contractile response. OR Give the summary of the electrical and the biochemical event in muscle contraction.

Answer»

Events in Muscle fibre: 

(i) A nerve impulse arriving at neuromuscular junction stimulates contractile response. 

(ii) Due to the Depolarisation of the surface of sarcomeres, it spreads quickly. 

(iii) Neurotransmitter is released at the neuromuscular junction. 

(iv) It enters into the sarcomere through membrane channel. Na+ moves inside the sarcomere. 

(v) It is called inflow of Na+

(vi) Action potential is generated in the sarcomere Action potential travels to the full length of muscle fibre. 

(vii) The sarcoplasmic reticulum, then, releases the Ca++ which is stored here. 

(viii) It binds to the specific sites found in the troponin of the thin actin filament. 

(ix) Change takes place in troponin and active sites of F-actin are exposed to myosin head. 

(x) Myosin head shows Mg++ dependent ATPase activity. 

(xi) During relaxation of muscle, Ca++ is pumped back into the sarcoplasmic reticulum. 

(xii) Consequently, the troponin component is freed to inhibit the active sites for myosin head. Cross bridges are broken. 

(xiii) The thin filaments assume their normal position. 

(xiv) The muscle fibre then comes in relaxed state.