Plant Reproduction and Germination

• Germination is the process by which an organism grows from a seed or similar structure. 
• The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm.substances present in seed coats and cotyledons of seeds inhibit seed germination are Abscisic acid, Phenolic acid and Ferulic acid. 
• Abscisic acid (ABA) reversibly arrests embryo development at radicle, growth initiation, inhibiting the water uptake which accompanies embryo growth.
• Hence,  substances present in seed coats and cotyledons of seeds inhibit seed germination is  Abscisic acid, Phenolic acid and Ferulic acid.
• So, the correct answer is 'All of the above'.

At a basic level, seeds have three requirements to permit germination. These are:

1. Water (during absorption and subsequent stages of growth).
2. Oxygen (for respiration).
3. Temperatures adequate for metabolism and growth.

Oxygen is one of the factors that play an important role in the germination of seeds. Oxygen in the presence of enough moisture causes respiration to start. This creates energy for the germination process.

Germination may also be defined as protrusion of embryonic axis from the seed to resume growth. The external factors that affect seed germination are as follows:

Most seeds go through a cold period before germination. Helps prevent seeds from sprouting as soon as they mature.

Soil is ploughed before seeds are sown. It is done to ensure the supply of oxygen in soil. Aerated soils can only support the growth of plants. Thus, if the seeds are sown deeply it will not germinate.

Water, air and suitable temperature are necessary for seed germination. Water is necesssary for germination because food is stored in the seeds in dry condition, but the developing embryo cannot utilize this dry food. Food can be utilized in liquid form only and seeds can utilize only dissolved oxygen. Excess water stops germination because once all the dissolved oxygen is utilised by the seed, further germination is not possible as the life supporting oxygen is now lacking. So, the correct answer is 'Water'.

In general seeds within the fruit do not germinate due to germination inhibitory effects of fruit pulp except viviparous germination. Tomato seeds loose viability and germination percentage up to 50% within one year after fresh extraction. Ferulic acid is a growth inhibitor in tomato. So, the correct answer is 'Presence of ferulic seed'.

All seeds need water, oxygen, and proper temperature in order to germinate. Some seeds require proper light also. Some germinate better in full light while others require darkness to germinate. Rice seeds and typha seeds are able to germinate anaerobically by means of coleoptile elongation. Pea seeds require oxygen to germinate. So, the correct answer is ‘Both B and C’.

During germination rapid cell division takes place. Energy is required for cell division. This energy is obtained from oxidation. The oxygen required for oxidation is supplied by the air. So, air is necessary for seed germination. Seeds placed deep in the soil do not germinate because they are unable to get sufficient oxygen. So, the correct answer is 'Unable to get sufficient oxygen'.

A. Xanthium has seed dormancy due to present of germination inhibitors like abscisic acid, phenolic acid, ferulic acid, coumarin, short fatty acids and cyanogenic chemicals. So, it  won’t germinate in the presence of favorable condition.

B. Pisum sativum- Don’t have germination inhibitors. So, it germinate in the presence of favorable condition.

C. Zea mays- Don’t have germination inhibitors. So, it germinate in the presence of favorable condition.

So, the correct answer is ‘Both B and C’.

Conditions necessary for germination: Water, air and suitable temperature are necessary for seed germination.

Water is necesssary for germination because food is stored in the seeds in dry condition, but the developing embryo cannot utilize this dry food. Food can be utilized in liquid form only and seeds can utilize only dissolved oxygen. Excess water stops germination because once all the dissolved oxygen is utilised by the seed, further germination is not possible as the life supporting oxygen is now lacking.

During germination rapid cell division takes place. Energy is required for cell division. This energy is obtained from oxidation. The oxygen required for oxidation is supplied by the air. So, air is necessary for seed germination.

Suitable temperature is necessary because low temperature retards the embryo activity and high temperature destroys the delicate embryo tissue. 

So, the correct answer is 'Oxygen, moisture and suitable temperature'

Onion seeds are known to be negatively photoblastic, meaning their germination is inhibited by light. Other options like bean and maize are generally indifferent to light.

Air (oxygen) is necessary for seed germination(Pea seed). During germination rapid cell division takes place. Energy is required for cell division. This energy is obtained from oxidation. The oxygen required for oxidation is supplied by the air. So, air is necessary for seed germination. So, the correct answer is ‘Oxygen’.