Seed becomes plant - class-XI

Germination of seed require a lot of energy and the rate of respiration increases and need of oxygen also increases as the metabolic rate is very high at this time.

• 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.

<i><span>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’.

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’.

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 'Light'.

The process of seed germination depends on many factors like temperature, water, oxygen and sometime light. Seeds usually germinate within a wide temperature range. Hence, essential requirement for seed germination to take place is water and oxygen. Germination cannot take place without sufficient supply of water. In presence of sufficient moisture, water is taken up by seed. Oxygen is essential for aerobic respiration. 

Autonomic movement is the spontaneous movement of the protoplasm seen in aquatic plants due to internal stimulus. It is not related to the external stimulus. Movement of cilia and flagella is an example of autonomic movement. A movement shown by a plant part in response to an external factor is called as paratonic movement. In this, the direction of movement is controlled by the direction of the stimulus. 

Positive photoblastic seeds require white light to germinate in dark the growth does not occur. this response is controlled by phytochromes and includes the plants like mango, wheat etc.

Pulse seeds are rich in starch. During germination, the enzyme amylase breaks down these starch reserves into simpler sugars to provide energy for the growing embryo.

Phosphorylase is the enzyme responsible for the reversible conversion of starch to glucose-1-phosphate, playing a key role in starch synthesis and degradation in developing seeds.

Positively photoelectric seeds include lettuce, while non-photoelectric seeds include cucumber. Anaerobic germination is possible in rice, and acid scarification is often required for hard-coated seeds like Leucaena.

Vivipary is a condition where the embryo derives nutrition from the parent and is attached it attains maturity. In plants, vivipary refers to the development of a seedling within an attached fruit so that the seedling can derive nutrition.

Ethylene is highly effective in fruit ripening. It enhances the respiration
rate during ripening of the fruits. 

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. When a seed is exposed to the proper conditions, water and oxygen are taken in through the seed coat. 

Phytochrome is a pigment found in plants which is involved in various plant processes like seed germination. Seed germination requires sufficient amount of P$ _{pr}$. P$ _r$ is synthesized by germinating seeds and is converted to P$ _{pr}$ when exposed to red light. However, when seeds are exposed to far-red light, they will not germinate as P$ _{pr}$ is converted to P$ _r$.

Germination of most of the seed is under the control of light. Usually, red light induces seed germination whereas far-red light suppresses germination. However, light inhibits seed germination of Mediterranean plants like Allium. It usually grows as crowded vegetation and germination take place in dark condition.

Negative photoblastic seeds are those seeds which are able to grow in dark and while light inhibits their growth and seed is unable to come out from underground. Plants like onion, lily, and nigella re of such type.

A cotyledon is part of the embryo within the seed of a plant. Often when the seed germinates or begins to grow, the cotyledon may become the first leaves of the seedling. contains protein, fats, and starches which provide energy for the developing seedling. The cotyledons provide a similar function. These are the seed leaves and they also contain storage of food for the developing plant. The cotyledons in some cases are major photosynthetic producers during germination.