Question

Read the given passage and answer the questions 1 to 5 that follow : 1 x 5 = 5

Colloidal particles always carry an electric charge which may be

either positive or negative. For example, when AgNO3 solution is added to

KI solution, a negatively charged colloidal sol is obtained. The presence of

equal and similar charges on colloidal particles provide stability to the

colloidal sol and if, somehow, charge is removed, coagulation of sol occurs.

Lyophobic sols are readily coagulated as compare to lyophilic sols.

1. What is the reason for the charge on sol particles ?

2. Why the presence of equal and similar charges on colloidal particles provide

stability ?

3. Why a negatively charged sol is obtained on adding AgNO3 solution to KI

solution ?

4. Name one method by which coagulation of lyophobic sol can be carried out.

5. Out of KI or K2SO4, which electrolyte is better in the coagulation of positive sol ?​

Answer 1

A staminate flower contains stamens only while a pistillate flower only contains carpels or pistils. This is the major difference. Stamens are male reproductive organs while pistils are female reproductive structures.

Out of the many other structures of a flower, stamens and pistils are the reproductive parts. In angiosperms, they participate in reproduction. Stamens consist of anthers and filaments which enclose male gametes. Pistil on the other hand is a female reproductive structure consisting of stigma, ovary and style. Though almost all flowers can be classified into pistillate and staminate flowers, some flowers have both male and female structures in the same flower.

Staminate Flowers

Consists of male reproductive structures only and is an androecious or male flower

Stamen, the male reproductive structure has two parts – filament and anther

It does not contain activated female reproductive parts

Cucumber a dioecious plant produces staminate flowers Chrysanthemum produces disc florets which are staminate flowers

Pistillate Flowers

Consists of female reproductive structures only known as the carpels or pistils

They do not have activated stamens. But they have a swollen base due to the presence of the ovary

Carpels have three parts – style, stigma and ovary

Pistillate flowers obtain pollens from other flowers for fertilization

Example – cucumber has pistillate flowers while bearing staminate flowers separately

Difference between Staminate and Pistillate Flowers

The table below depicts a few differences between Staminate and Pistillate Flowers

Staminate Flowers Pistillate Flowers

What are they?

Flower structures possessing stamens only Flower structures possessing pistils only

Flower type

Uni sexual Male flowers Uni sexual Female flowers

Stamens

Active stamens present Active stamens absent

Pistils

Active pistils absent Active pistils present

Produce

Pollen grains Ovules