Structural Variation in Angiospermic leaf

Leaf is a lateral dissimilar appendage of a plant body which arises on the node of stem and bears axillary bud on its axil. This note contains detail information about shape, apex, surface, margin, texture, phyllotaxy of leaf.

Summary

Leaf is a lateral dissimilar appendage of a plant body which arises on the node of stem and bears axillary bud on its axil. This note contains detail information about shape, apex, surface, margin, texture, phyllotaxy of leaf.

Things to Remember

  • Leaf is a lateral dissimilar appendage of a plant body which arises in the node of stem and bears axillary bud in its axil. 
  •  Leaves arising in a cluster or in a rosette form from the reduced stem known as disc than it is known as radical leaves. Eg; Radish, Turnip.
  • The mode of arrangement of leaves on the node of the stem is known as phyllotaxy. 
  • If single leaf arises on a node and leaves of adjacent nodes lie alternate to each other then it is known as alternate phyllotaxy. Eg; Tulsi
  • If a cluster of leaves arises on a node then it is known as whorled phyllotaxy.

 

MCQs

No MCQs found.

Subjective Questions

Q1:

What is mechanical energy? What are the types of mechanical energy? Write one example of each of them. 


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>The energy contained by a body at rest or in motion is called mechanical energy. It is the sum of kinetic energy and potential energy. There are two kinds of mechanical energy which are as follows,</p> <ul><li>Kinetic energy: water falling from the dam possess kinetic energy.</li> <li>Potential energy: water stored in a dam contain potential energy.</li> </ul>

Q2:

Derive the equation of kinetic energy.


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>The energy of a body in motion is called kinetic energy. For example, energy possessed by moving water is a kinetic energy.<br> If a body of mass &lsquo;m&rsquo; is moving with a velocity &lsquo;v&rsquo; then kinetic energy of a body is given by,<br> Kinetic energy (KE) = \(\frac{1}{2}\)mass \(\times\) (velocity)<sup>2</sup><br> i.e. K.E. = \(\frac{1}{2}\) m \(\times\) v<sup>2</sup><br> Where, <br> m = mass of the moving body<br> v = velocity of the moving body<br> The kinetic energy of a moving body is directly proportional to the product of the mass and square of the velocity of a body.</p>

Q3:

Define potential energy with two example and derive it equation.


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>The energy stored in or contained by a body at rest is calledpotential energy. Energy stored in a stretched rubber and energy of water stored in a dam are the examples of potential energy.<br> If a body of mass&rsquo;m&rsquo; is raised to a height &lsquo;h&rsquo;, the energy contained by the body (PE) is given by,<br><br> Potential Energy (PE) = m \(\times\) g \(\times\) h<br> \(\therefore\) PE = mgh.<br> Where, <br> g = acceleration due to gravity whose value is 9.8m/s<sup>2</sup>.</p>

Q4:

Define heat energy and sound energy with two examples of each.


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>The form of energy, which gives sensation of warmth, is called heat energy. The two sources of heat energy are sun and heater. Sound is a form of energy that is produced due to the vibration of a body. Any two sources of sound energy are loudspeaker and radio.</p>

Q5:

When one joule work is said to be done? Write down the formula relating the work, force and displacement.


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>The work dine is said to be 1 joule when 1N force can displace a body through 1m distance in the direction of the force applied. The formula relating the work, force and displacement is,<br> Work (W) = Force (F) \(\times\) Displacement (d).</p>

Q6:

A porter is standing with load on his back, Is he working or not?


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>When a porter stands with load on his back, he does not do any work or he is not working. Because in science, to do work, the force applied always should cover a certain distance. But the porter is not covering any distance.</p>

Q7:

Give any six examples of potential energy.


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>Any six examples of potential energy are given below:</p> <ol><li>The stretched rubber of catapult.</li> <li>Water in a dam.</li> <li>A hammer raised to strike.</li> <li>A compressed spring.</li> <li>A leg lifted to kick a ball.</li> <li>A stone raised at a certain height.</li> </ol>

Q8:

Gives any six examples of kinetic energy.


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>Any six examples of kinetic energy are as follows,</p> <ol><li>Water falling from the dam.</li> <li>A flying bird.</li> <li>A flying airplane.</li> <li>Water moving in a river.</li> <li>Moving vehicles.</li> <li>A fired bullet.</li> </ol>

Q9:

Define work done. Write types of work done with two examples of each.


Type: Short Difficulty: Easy

Show/Hide Answer
Answer: <p>Work is said to be done if a force applied on a body displace the body in the direction of the force. There are two types of work done which are as follows,</p> <ol><li>Work done against gravity<br> If a work is done against gravity, it is called the work done against gravity.<br> Examples: lifting water from the well and throwing ball upward.</li> <li>Work done against friction<br> The wok done against friction is called work done against friction.<br> Examples: pulling table in the ground and pushing vehicles on the road.</li> </ol>

Q10:

A man displaces an object to a distance of 10m by applying 50N effort. Calculated the work done.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Solutions:<br> We have,<br> Force applied (F) = 50N<br> Displacement (d) = 10m<br> According to the formula, <br> Work done (w) = F \(\times\) d<br> = 50 \(\times\) 10<br> = 500 joule<br> \(\therefore\) The work done is 500J.</p>

Q11:

A labor displaces a box to a distance of 25m. If the work done is 5000J then calculate the effort applied by the labor.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Solutions:<br> We have,<br> Force applied (F) = ?<br> Displacement (d) = 25m<br> Work done = 5000J<br> According to the formula, <br> Work done (w) = F \(\times\) d<br> Or, 5000 = F \(\times\) 25<br> Or, F = \(\frac{5000}{25}\)<br> Or, F = 200N<br> \(\therefore\) The effort applied is 200N.</p>

Q12:

Calculate the displacement of the body if the force applied is 100N and the work done is 2000J.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Solutions:<br> We have,<br> Force applied (F) = 100N<br> Displacement (d) = ?<br> Work done (w) = 2000J<br> According to the formula, <br> Work done (w) = F \(\times\) d<br> Or, 2000 = 100 \(\times\) d<br> Or, d = \(\frac{2000}{100}\)<br> Or, d = 2<br> \(\therefore\) The displacement of the body is 2m.</p>

Q13:

Calculate the amount of force applied when a body is displaced to a distance of 25m. The amount of work done is 2500 joule.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Solutions:<br> We have,<br> Force applied (F) = ?<br> Displacement (d) = 25m<br> Work done (w) = 2500J<br> According to the formula, <br> Work done (w) = F \(\times\) d<br> Or, 2500 = F \(\times\) 25<br> Or, F = \(\frac{2500}{25}\)<br> Or, F = 100N<br> \(\therefore\) The force applied is 100N.</p>

Q14:

If a person does 5000J of work in 50 seconds then what is the power of a person?


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Solutions:<br> We have,<br> Work done (w) = 5000J<br> Time taken (t) = 50 seconds<br> Power (P) = ?<br> By using formula,<br> Power (P) = \(\frac{ Work done (w)}{ Time taken (t)}<br> Or, P = \(\frac{w}{t}\)<br> Or, P = \(\fract{5000}{50}\)<br> Or, P = 100 watt<br> \(\therefore\) The power of the man is 100 watt.</p>

Q15:

Calculate the power of the men if he does 2000J of work in 50 seconds.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Solutions:<br> We have,<br> Work done (w) = 2000J<br> Time taken (t) = 50 seconds<br> Power (P) = ?<br> By using formula,<br> Power (P) = \(\frac{ Work done (w)}{ Time taken (t)}<br> Or, P = \(\frac{w}{t}\)<br> Or, P = \(\fract{2000}{50}\)<br> Or, p = 40 watt<br> \(\therefore\) The power of the men is 40 watt.</p>

Q16:

Calculate the time taken fir a men if he does 2500J of work and power is 50 watt.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Solutions:<br> We have,<br> Work done (w) = 2500J<br> Time taken (t) = ?<br> Power (P) = 50 watt<br> By using formula,<br> Power (P) = \(\frac{ Work done (w)}{ Time taken (t)}<br> Or, P = \(\frac{w}{t}\)<br> Or, P = \(\fract{2500}{t}\)<br> Or, 50 = \(\fract{2500}{t}\)<br> Or, t = \(\fract{2500}{50}\)<br> Or, t = 50 seconds<br> \(\therefore\) The time taken is 50 seconds.</p>

Q17:

Calculate the work done by a man if his power is 60 watt and time taken to do a work is 12 seconds.


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>Solutions:<br> We have,<br> Work done (w) = ?<br> Time taken (t) = 12 seconds<br> Power (P) = 60 watt<br> By using formula,<br> Power (P) = \(\frac{ Work done (w)}{ Time taken (t)}<br> Or, P = \(\frac{w}{t}\)<br> Or, 60 = \(\fract{work done }{12}\)<br> Or, Work done (w) = 60 \(\times\) 12<br> Or, Work done (w) = 720 joule</p> <p>\(\therefore\) The work done is 720 Joule.</p>

Q18:

What are the differences between power and energy?


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>The differences between power and energy are given below,</p>
<table width="641">
<tbody>
<tr>
<td width="321">
<p><strong>Energy</strong></p>
</td>
<td width="321">
<p><strong>Power</strong></p>
</td>
</tr>
<tr>
<td width="321">
<p>The capacity of doing work is called energy.</p>
</td>
<td width="321">
<p>The rate of doing work is called power.</p>
</td>
</tr>
<tr>
<td width="321">
<p>The SI unit of energy is joule (J).</p>
</td>
<td width="321">
<p>The SI unit of power is watt (W).</p>
</td>
</tr>
<tr>
<td width="321">
<p>Energy of the body is measured by the total work done by the body. Time is not considered.</p>
</td>
<td width="321">
<p>Power is measured by work done in unit time.</p>
</td>
</tr>
</tbody>
</table>

Q19:

What are the differences between potential energy and kinetic energy?


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>The differences between potential energy and kinetic energy are given below,</p>
<table width="648">
<tbody>
<tr>
<td width="324">
<p><strong>Potential energy</strong></p>
</td>
<td width="324">
<p><strong>Kinetic energy</strong></p>
</td>
</tr>
<tr>
<td width="324">
<p>The energy possessed by a body in rest is called potential energy.</p>
</td>
<td width="324">
<p>The energy possessed by a body in its motion is called kinetic energy.</p>
</td>
</tr>
<tr>
<td width="324">
<p>The potential energy of the body depends on its mass, height and change in condition.</p>
</td>
<td width="324">
<p>The kinetic energy of a body depends on its mass and speed.</p>
</td>
</tr>
<tr>
<td width="324">
<p>Example: stretched rubber</p>
</td>
<td width="324">
<p>Example: a hammer striking a nail.</p>
</td>
</tr>
</tbody>
</table>

Q20:

What are the differences between workdone and energy?


Type: Long Difficulty: Easy

Show/Hide Answer
Answer: <p>The differences between work done and energy are given below,</p>
<table width="653">
<tbody>
<tr>
<td width="327">
<p><strong>Work done</strong></p>
</td>
<td width="327">
<p><strong>Energy</strong></p>
</td>
</tr>
<tr>
<td width="327">
<p>Work is said to be done when a body moves in the direction of the applied force.</p>
</td>
<td width="327">
<p>The capacity of doing work is called energy.</p>
</td>
</tr>
<tr>
<td width="327">
<p>It is mathematically written as Work done (w) = Force (F) \(\times\) Displacement (d).</p>
</td>
<td width="327">
<p>It is either given as K.E = \(\frac{1}{2}mv<sup>2</sup> or P.E = mgh.</p>
</td>
</tr>
<tr>
<td width="327">
<p>For example,when aboy is displaced (d) from one position to another by applying force (F).</p>
</td>
<td width="327">
<p>For example, sound energy, mechanical energy, kinetic energy, etc.</p>
</td>
</tr>
</tbody>
</table>
<p>&nbsp;</p>
<p>&nbsp;</p>

Q21: Define energy.
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: The ability or capacity to do work is called energy.

Q22: Define potential energy.
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: The energy possessed by a body at rest is called potential energy.

Q23: What is heat energy?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Heat energy is a form of energy which gives sensation of warmth to us.

Q24: What is sound energy ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Sound energy is a form of energy which gives sensation of hearing.

Q25: What is light energy ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Light energy is a form of energy which gives sensation of vision.

Q26: What is magnetic energy ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: The energy possessed by a magnet is called magnetic energy.

Q27: What is chemical energy ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: The energy produced from the chemical reaction of a substance is called chemical energy.

Q28: Define power.
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Power is defined as the rate of doing work.

Q29: What is 1 joule work ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: When 1N force displaces a body through 1m in the direction of force is called 1 joule work.

Q30: What is nuclear energy ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: The energy which is obtained through nuclear fission or nuclear fusion is called nuclear energy.

Q31: What is SI unit of power ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: The SI unit of power is watt (W).

Q32: What is SI unit of energy ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: The SI unit of energy is joule.

Q33: Define electrical energy.
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Electrical energy can be defined as the energy produced due to the continuous flow of electrons through a conductor.

Q34: What do you mean by work done ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Work is said to be done if a force applied on a body displaces the body in the direction of the force.

Q35: Write any two sources of heat energy.
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Any two sources of heat energy are sun and petroleum.

Q36: What is one watt power ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: The rate of doing one joule work in one second time is called one watt power.

Q37: Write any two sources of sound energy ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Any two sources of sound energy are loudspeaker and radio.

Q38: What is the major source of light energy ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Sun is the major source of light energy.

Q39: Define kinetic energy.
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: The energy possessed by a body in motion is called is called kinectic energy.

Q40: What do you mean by work done against friction ?
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: If the work is done against the frictional force then it is called work done against friction.

Q41: Give any two examples of work done against gravity.
Type: Very_short Difficulty: Easy

Show/Hide Answer
Answer: Any two examples of work done against gravity are lifting bag from the ground and lifting water from the well.

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Structural Variation in Angiospermic leaf

Structural Variation in Angiospermic leaf

Shape of leaf

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source:waynesword.palomar.edu

Acicular: Elongated pointed needle-shaped leaf. Eg; Pinus

Linear: Elongated, narrow flattened leaf. Eg; Grasses, Zea Hays.

Lanceolate: Elongated sword-like leaf. Eg; Nerium

Elliptic: Ellipse shaped leaf. Eg; Psidium Gwasava (Gawa)

Cordate: Hard shaped leaf or leaf with a notched base and pointed apex. Eg; Piper betel.

Obcordate: Leaf with notched apex and rounded or pointed base. Eg; Bauhinia

Ovate: Egg-shaped leaf or leaf with the broad base and narrow apex. Eg; Hibiscus

Obovate: Leaf with broad apex and narrow or pointed base. Eg; Terminalia

Oblong: Elongated rectangular leaf. Eg; Musa( Banana)

Hastate: Arrowhead-shaped leaf. Eg; upper leaf of Brassica Campestris.

Lyrate: Lyre-shaped leaf or leaf with large terminal lobe and small lateral lobes. Eg; Brassica Campestris

Apex of leaf

Acute: Leaf with a pointed apex.

Obtuse: Leaf with rounded apex.

Accuminate: Leaf with pointed apex in which extreme apex is drawn out into an elongated tale like structure.

Mucronate: Leaf with rounded or pointed apex in which short pointed outgrowth appears at the extreme tip.

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source:www.cactus-art.biz

Surface of Leaf

Glabrous: Leaf with a smooth or non-hairy surface.

Glaucous: Leaf with the smooth and shiny surface. Eg: Rubber plant.

Pubescent: Leaf with the hairy surface. Eg: Geranium

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source:www.discoverlife.org

Margin of Leaf

Entire: Leaf with the smooth margin.

Repand: Leaf with slightly or lightly wavy margin.

Sinuate: Leaf with deeply wavy margin.

Serrate: Leaf with a saw - like margin in which teeth are directed towards the apex.

Serrulate: Leaf with finely serrated margin.

Dentate: Leaf with toothed margin in which teeth are outwardly directed.

Runcinate: Leaf with a saw- like margin in which teeth are directed towards the leaf base.

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source:www.infovisual.info

Texture of leaf

Herbaceous: Thin and soft textured leaf. Eg; Rose

Coriaceous: Thick firm and leathery texture. Eg; Rubber plant

Succulent: Thick and fleshy leaf which stores water in the form of mucilage. Eg; Aloe vera

Duration of leaf

Caducous: Leaves falling off much earlier in the life.

Deciduous: Leaves remaining intact at least for one season.

Persistent: Leaves remaining intact for whole life.

Insertion of Leaf

Cauline: Leaves arising on the main stem. Eg; Maize

Ramal: Leaves arising on the branches. Eg; All trees

Radical: Leaves arising in a cluster or in a rosette form from the reduced stem known as disc than it is known as radical leaves. Eg; Radish, Turnip.

Phyllotaxy

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source:www.tutorvista.com

The mode of arrangement of leaves on the node of the stem is known as phyllotaxy. It is of three types;

Alternate/Spiral

If single leaf arises on a node and leaves of adjacent nodes lie alternately to each other then it is known as alternate phyllotaxy. Eg; Tulsi

Opposite

If a pair of leaves arise on a node and lie opposite to each other than it is known as opposite phyllotaxy. If a pair of leaves on adjacent nodes occur on the same plane than it is known as superposed opposite phyllotaxy. If a pair of leaves on adjacent node lie perpendicular to each other than it is known as decussate opposite phyllotaxy.

Whorled:

If a cluster of leaves arises on a node then it is known as whorled phyllotaxy.

Lesson

Angiosperm

Subject

Biology

Grade

Grade 11

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