Q: How many meiosis are required for the formation of 100 grains of wheat.

In plants, four male gametes are produced by a single microspore via meiosis. So, after 25 divisions, 100 male gametes will be produced. Also, one female gamete is produced after a single meiotic division. Hence, 100 eggs will be produced in 100 divisions. Hence, a total of 125 meiotic divisions are required for the formation of 100 wheat grains.So, the correct answer is '125'.

Question 1

Identify each part in a flowering plant and write whether it is haploid (n) or diploid (2n).(a) Ovary (b) Anther (c) Egg (d) Pollen (e) Male gamete (f) Zygote

Accepted Answer

(a) Ovary - It is the female part of the plant which has ovules. It is a diploid (2n) structure.(b) Anther - It is the male part of the flower and contains pollen grain. It is a  diploid structure (2n).(c) Egg - Ovules are known as egg. It is female gamete present  in the ovary. It is a haploid structure (n).(d) Pollen - Pollens are male gamete. It is a haploid (n) gamete.(e) Male gamete - Pollens are male gamete. It is a haploid (n) gamete.(f) Zygote - It is formed by the fusion of male and female gamete. It is a diploid structure (2n).

Question 2

Discuss the different modifications of leaves.

Accepted Answer

Modification Definition Example 1) TendrilsThe leaves are modified into slender wiry and coiled structures called leaf tendrils and support climbers to climb Pisum Sativum 2) SpinesThe leaves modified into a pointed structure and usually protect them from herbivores. Opuntia 3) PhyllodeIt is a green extended structure formed by the modification of petiole or rachis of leaf that carries out photosynthesis. Acacia 4) Storage leavesLeaves become fleshy due to storage of water and food material. Aloe 5) CotyledonsThe mature embryo shows either one or two cotyledons. Angiosperms and gymnosperms 6) Leaf bladdersSome of the leaves of aquatic plants modified into leaf bladders to trap small insects. Utricularia 7) Leaf PitcherLamina of the whole leaf is modified into a lid known as a pitcher which traps insects to fulfil the need of nitrogen. Nepenthes

Question 3

Explain the structure of a leaf with the help of a labelled diagram.

Accepted Answer

Leaves are vital to the survival of plants. They help plants in a variety of ways, including producing food and oxygen through photosynthesis, balancing water loss, regulating gas exchange, and transporting the products of photosynthesis.A leaf has two main parts:(1) Petiole- the stalk that supports a leaf in a plant and attaches the leaf blade to the stem. (2) Lamina- the green flat part of a leaf that is specialized for photosynthesis. The lamina contains the following parts:(i) Veins- the lines on the green flat part in a leaf that provide support for the leaf and transport both water and food.(ii) Midrib- The central, thick, linear vein that runs along the length of a leaf is called midrib.

Question 4

Differentiate between racemose and cymose inflorescence

Accepted Answer

Racemose inflorescence Cymose inflorescence This is an indefinite or indeterminate type of inflorescence This is a definite or determinate type of inflorescence The main axis does not end the growth with a flower The main axis ends the growth with a flower The flowers are borne in acropetal succession, that is, lower ones are older and upper ones are younger flowers The flowers are borne in basipetal succession, that is, lower ones are younger flowers and upper ones are older flowers Flowers are borne laterally  Flowers are borne terminallyThe opening of flowers occurs at short intervals Opening of successive flowers take long intervals

Question 5

Name the male and female reproductive parts in plants.

Accepted Answer

1) The male reproductive part in a plant is called stamen.It consists of anther and filament.The anther is a lobed structure which produces pollen grains.The filament is a slender stalk-like structure.2) The female reproductive part in a plant is called the pistil.It consists of three parts- stigma, style and ovary.The sticky part at the top called a stigma.A thin tube passing down is called a style.A swollen sac-like structure at the bottom is called an ovary. The pollen grains are transferred onto the stigma which then travels down the style into the ovary, where it meets with the ovules and fertilization takes place.

Question 6

What is aestivation? Describe its various types found in petals.

Accepted Answer

Aestivation is the mode of arrangement of sepals or petals in the floral bud with respect to the other members of the same whorl.It is divided into five main types:-A)Valvate Aestivation:-when sepals or petals are arranged in a whorl and just touch margin of one another as seen in Calotropis.B)Twisted Aestivation:-One margin of appendages overlaps that of the next one as seen in China rose.C)Imbricate Aestivation:- Margin of flower overlaps but not in a particular manner as in Gulmohar.D)Vexillary Aestivation:-When five petals differentiated into large standard petal or vexillum which overlaps two lateral petals called wings which in turn overlap the smallest anterior petals called keel and is the characteristic feature of the papilionoceae family also called as papilionaceous aestivation.E)Quincuncial Aestivation:-When the petals are arranged in a manner that two petals are completely out of the whorl and two are completely inside while one left is half outer and half is inner side present as seen in Ranunculus.

Question 7

Describe the various types of placentations found in flowering plants.

Accepted Answer

Placentation refers to the arrangement of ovules inside the ovary. It is of five basic types:(A) Marginal placentation-The ovary in which the placenta forms a ridge along the ventral suture of the ovary and the ovules develop on two separate rows is known to have marginal placentation. This type of placentation is found in peas.(B) Parietal placentation-When the ovules develop on the inner walls of the ovary, the ovary is said to have parietal placentation.C) Axile placentation-In axile placentation, the placenta is axial and ovules are attached to it. Examples include China rose, lemon and tomato.(D) Basal placentation-The ovary in which the placenta develops from its base and a single ovule is found attached to the base is said to have basal placentation. It is found in marigold and sunflower.(E) Free central placentation-In free central placentation, the ovules develop on the central axis while the septa are absent. This type of placentation is found in Dianthus and primrose.

Question 8

Phylogenetic system of classification is based on

Accepted Answer

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Question 9

How many meiosis are required for the formation of 100 grains of wheat.

Accepted Answer

In plants,&#10;four male gametes are produced by a single microspore via meiosis. So, after 25&#10;divisions, 100 male gametes will be produced. Also, one female gamete is&#10;produced after a single meiotic division. Hence, 100 eggs will be produced in&#10;100 divisions. Hence, a total of 125 meiotic divisions are required for the&#10;formation of 100 wheat grains.So, the correct answer is '125'.

Question 10

Observe the diagram given below. What happens after the above stage?

Accepted Answer

A fertilized flower gives rise to a fruit. A fruit is defined as a ripened ovary. It protects the seeds. The ovules are the embryos from which seed develop after fertilization. The pericarp is the fruit wall that develops from the ovary wall. Thus the correct answer is option B.