The question asks about the primary factor limiting the distribution of plankton in aquatic ecosystems. Plankton are organisms that drift in water, unable to swim against currents. Understanding their nature helps identify the most significant limiting factor.
Correct Option: C) Water currents — Plankton are defined as organisms that drift with water currents. Therefore, their distribution is fundamentally controlled by these currents, which transport them across aquatic ecosystems.
The question asks to identify regions in India where coral reefs are found. This requires knowledge of the geographical distribution of coral reefs in India.
Based on this analysis, coral reefs are found in Andaman and Nicobar Islands, Gulf of Kachchh, and Gulf of Mannar.
A) 1, 2 and 3 only. This option correctly identifies the three regions in India that are home to significant coral reef ecosystems.
To determine which factor does NOT directly affect phytoplankton biodiversity, we need to understand the primary environmental requirements for phytoplankton growth and survival. Phytoplankton are microscopic marine algae that form the base of the marine food web and perform photosynthesis. Their biodiversity is influenced by factors that directly impact their physiological processes and competitive interactions.
Based on this analysis, light, iron, and temperature are direct environmental factors influencing phytoplankton physiology and competition, whereas wind speed's influence is indirect.
Correct Option: D) Wind speed
The question asks about a specific nutrient requirement for diatoms. To answer this, we need to recall the unique structural components of diatoms and the chemical elements they utilize to build these structures.
Correct Option: B) Silicate is the primary nutrient required in significant amounts by diatoms because their cell walls (frustules) are composed of silica.
This question asks about the role of iron in phytoplankton biology. To answer this, we need to recall the essential nutrients for phytoplankton and the specific functions of iron in their metabolic processes, particularly in relation to their growth and distribution in oceans.
Correct Option: C) It limits their growth in many ocean areas
This statement is accurate. Iron is a critical micronutrient for phytoplankton, essential for photosynthesis and nitrogen fixation. Its scarcity in vast regions of the ocean (known as High-Nutrient, Low-Chlorophyll or HNLC areas) directly limits phytoplankton growth and productivity, despite the presence of other abundant macronutrients.
The question describes a unique tidal phenomenon where the sea water recedes significantly, allowing people to walk on the seabed, and then returns. This phenomenon occurs twice a day. We need to identify the location in India where this is observed.
Correct Option: C) Chandipur is the location in India where the sea recedes several kilometers twice a day, allowing people to walk on the sea floor.