Mineral Toxicity: Symptoms & Deficiency

What Is Mineral Toxicity?

Mineral toxicity is a condition in which essential minerals required for life are consumed in an abnormally large amount, which causes harm to good health. As the saying goes, "Too much of a good thing is bad," this works for minerals, too. In essence, although the minerals do play critical roles in most of the body functions and plant growth—which are ineluctable—too many of them may hamper biological procedures and bring damage.

Importance of Mineral Balance

The amount of minerals is taken in is important to ensure that there is a delicate balance. The seven essential micro-nutrients need to be in the required proportions in both plants and animals. Too much of a certain mineral will make it toxic while too little will make it deficient. This balance is key to health and functioning.

Functions of Mineral Elements

The importance of mineral elements in plants and animals is quite diverse their functions include:

• Carries electrons: Participates in various biochemical reactions.

• Enzyme activation: Most of the minerals act as cofactors for enzymes for metabolic functions.

• Osmotic regulation: Helps to maintain the osmotic pressure, necessary for turgor and growth of plants.

• Form structural elements: Minerals help in the integrity of cells and tissues.

Effect Of Mineral Toxicity On Plants

Overconsumption by plants of these minerals results in a series of effects that are harmful to the health of the plants. Some of the symptoms of mineral toxicity include:

1. Cessation of Roots and Leaves: Plants usually show stunted growth and very poor leaf development.

2. Disruption of Cells: A toxic amount can seriously disrupt the cell structure and the cell walls.

3. Reduced Branching: An excess of these minerals will arrest the normal branching pattern of a plant.

4. Changes in pH Levels: Small changes in the pH of the cytosol will damage cellular functions.

5. Enzyme Misalignment: In this case, enzymes do not align the right way with respective substrates and cause metabolic dysfunction.

6. Chlorosis: This occurs due to a lack of chlorophyll production.

7. Oxidative Stress: It results from the generation of excess reactive oxygen species within a cell and potentially damages cellular components.

8. Cell Death: Exploitation of excess toxicity conditions, causing cell and tissue death.

Mechanisms Of Toxicity

The mechanism of mineral toxicity differs from mineral to mineral. For example :

Manganese Toxicity

High manganese levels can compete with magnesium and iron absorption. Hence, the actual deficiency of the said important minerals in plants. Brown spots appear on the leaves, which very often are surrounded by chlorotic veins.

Iron Toxicity

Excess iron can lead to oxidative stress with consequent damage to chloroplasts and reduced photosynthetic efficiency.

Copper Toxicity

A high level of copper can inhibit the ability of the plant to absorb essential nutrients, resulting in stunted growth and discolouration.

Toxicity Levels in Plant Tissues

Toxicity is the primary consideration of the concentration of mineral ions in plant tissue. In general, if the concentration would have to decrease the dry weight of tissues by about ten per cent, then it is regarded as toxic. Such concentration levels are widely different among the different kinds of plant species due to different nutritional requirements and tolerance levels.

Interrelations and Mineral Antagonism

A critical interaction in mineral toxicity is the antagonism between various minerals. An excess intake of one element arrests the uptake of another. High levels of potassium, for instance, prevent magnesium absorption, resulting in deficiencies and symptoms of deficiency.

Prevention and Management

Mineral toxicity can be prevented and managed by following steps:

• Maintain a balanced use of the fertilisers in crops.

• Check soil pH and the concentration of metals through laboratory testing

• Use chelating agents and bioremediation plants like Brassic species for sustainable agricultural practices.

• Follow crop rotation and organic farming practices to prevent accumulation of certain minerals in the soil.

Mineral Toxicity NEET MCQs (With Answers & Explanations)

The key concepts to be covered under this topic for different exams are:

• Mineral toxicity of different elements

• Effect of mineral toxicity

Practice Questions for NEET

Q1. The mineral ion concentration at which the dry weight of a tissue is reduced by 10% is called

1. Optimum concentration

2. Critical concentration

3. Toxic concentration

4. Ion concentration

Correct answer: 3) Toxic concentration

Explanation:

The toxic concentration of a mineral ion is the level at which the dry weight of plant tissue is reduced by 10%. This threshold varies among micronutrients and differs from plant to plant. For instance, manganese becomes toxic at concentrations above 600 micrograms per gram in soybean, while in sunflower, toxicity occurs only beyond 5300 micrograms per gram. Such variability highlights the differing tolerances and nutrient requirements of plants, underscoring the importance of maintaining optimal nutrient levels for healthy growth.

Hence, the correct answer is option 3) Toxic concentration.

Q2. Which one of the following is not an essential mineral element for plants while the remaining three are?

1. Cadmium

2. Phosphorus

3. Iron

4. Manganese

Correct answer: 1) Cadmium

Explanation:

Cadmium is a toxic heavy metal pollutant that accumulates in plants, disrupting metabolic processes and leading to growth inhibition. Along with lead, zinc, mercury, and other heavy metals, it causes heavy metal poisoning that affects enzyme activity and nutrient uptake.

Hence, the correct answer is option 1) Cadmium.

Q3. Chlorosis occurs due to the lack of________ essential elements

1. Ca, Mg, K and Cu

2. N, K, S, and Mo

3. N, S, and Mo

4. N, K, S, Fe, Mg, Mo, Mn

Correct answer: 4) N, K, S, Fe, Mg, Mo, Mn

Explanation:

Chlorosis is the loss of chlorophyll which occurs due to the lack of essential elements like N, K, S, Fe, Mg, Mo, Mn, and Zn. As these elements play a vital role in chlorophyll synthesis and other metabolic processes, when the plant lacks this nutrient, it is not able to produce enough chlorophyll which eventually leads to chlorosis. This will finally inhibit the plant's photosynthetic abilities.

Hence, the correct answer is option 4) N, K, S, Fe, Mg, Mo, Mn.

Also Read:

• MCQs on Mineral Toxicity

• What is Hydroponics Farming?

• Nitrogen Metabolism

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