Problem 108 - Objective Biology for NEET

Question

In virus infected plants the following symptoms can be observed (a) Mosaic formation and stunted growth (b) Leaf rolling and curling (c) Yellowing and vein clearing (d) All of these

Step-by-Step Solution

Answer

(d) All of these

Step 1: Understanding The Question

Recognize that the question is asking for symptoms of virus infection in plants. You'll need knowledge about the topic to answer this.

Step 2: Review Symptoms

Review each answer choice (a, b, c, and d) to determine if each one can be a symptom of viral infection in plants. Symptoms listed in options (a), (b), and (c) including mosaic formation, stunted growth, leaf rolling and curling, yellowing, and vein clearing are all typical symptoms of virus infection in plants.

Step 3: Choose The Correct Answer

Having verified the possible symptoms, the final step is to select the option that comprehensively lists all of them. Option (d) 'All of these' is the correct answer, as all the symptoms listed in options (a), (b), (c) are potential virus infection symptoms in plants.

Key Concepts

Mosaic Formation in Plants

Mosaic patterns on leaves are a distinctive symptom often associated with virus infections in plants. These irregular patches of different colors, primarily greens and yellows, give the leaves a mottled appearance. The contrasting hues create a 'mosaic' like art piece, hence the name. This symptom can detract from the plant's ability to conduct photosynthesis effectively due to the disrupted distribution of chlorophyll.

Mosaic patterns can also affect the overall plant vigor, since the energy production is hindered. Additionally, mosaic symptoms indicate that the plant’s immune response has been activated against the virus, often leading to further physiological changes beyond coloration.

Plant Stunted Growth

Stunted growth in plants is a clear sign that something is amiss. Virus infections can severely impact a plant's development, resulting in shorter stature and reduced leaf and stem size. This happens because the virus interferes with the plant's internal processes, such as nutrient uptake and hormonal balance, which are critical for growth.

In addition, when a plant is fighting an infection, it diverts resources to defense mechanisms instead of growth. The restricted development not only affects the aesthetic quality of ornamental plants but can also lead to significant yield losses in crops.

Leaf Rolling and Curling

Leaves that curl or roll inwards can be symptomatic of various issues, including viral infections. This reaction is a defensive move by the plant to reduce the surface area exposed to the virus. Leaf rolling and curling can also be a plant's attempt to conserve water and reduce transpiration as it combats the infectious agent.

However, this modification in leaf structure can compromise the plant's overall health because the reduced surface area limits photosynthesis and gas exchange. Recognizing this symptom is vital for early virus detection and potentially mitigating further spread and damage.

Plant Yellowing and Vein Clearing

Yellowing, or chlorosis, is the loss of green pigment in the plant leaves, often starting at the veins and spreading outward. Vein clearing is a related symptom where the veins themselves become pale or colorless. Both phenomena are linked to the disruption in the transportation of essential nutrients and reduced chlorophyll production.

Additionally, these changes can weaken the plant's structural integrity and decrease its ability to support itself, leading to secondary symptoms and vulnerability to other pathogens. Being attentive to these changes can facilitate prompt intervention, which is crucial for the plant's survival and health.