Biology Test 297

• Plants exhibit indeterminate growth, meaning they grow continuously throughout their lifespan. This type of growth is characterized by the ability of plants to keep increasing in size and often in complexity, due to the presence of meristematic tissues that retain the ability to divide and differentiate.
• This contrasts with determinate growth seen in most animals, where growth stops after reaching a certain stage of development.
• An interesting fact about indeterminate growth is that it allows plants to adapt and respond to their environment continuously, through processes such as branching and the formation of new leaves and flowers.

Lichens are very sensitive to sulfur dioxide and other air pollutants, which makes them excellent biological indicators of air quality. Their absence in an area often indicates high levels of pollution, particularly sulfur dioxide, making Option A correct.

Identification of Organism requires intensive laboratory and field studies. The collection of actual specimens of plant and animal species is essential and is the prime source of taxonomic studies. It is used for classification of an organism and the information gathered is also stored along with the specimens.

Budding is a form of asexual reproduction where a new organism develops from an outgrowth or bud due to cell division at one particular site. This method is seen in simple organisms such as yeast and Hydra. It allows for the rapid multiplication of individuals without the need for sexual reproduction, ensuring genetic consistency across generations. An interesting additional fact is that budding, as a form of asexual reproduction, plays a crucial role in the survival and dispersal strategies of many organisms, allowing them to exploit and colonize habitats efficiently.

Mosses, being non-vascular plants, do not have a true vascular system like xylem and phloem found in higher plants for transporting water and nutrients. Instead, they absorb water and nutrients directly through their leaves, which is a characteristic adaptation to their environment. This direct absorption is facilitated by the mosses' small size and the moist habitats in which they typically live.

As we go higher from species to kingdom, the number of common characteristics goes on increasing. Lower the taxa, more are the characteristics that the members within the taxon share. Higher the category, greater is the difficulty of determining the relationship to other taxa at the same level.

In Bryophytes, the main plant body is the gametophyte, which is haploid and produces gametes. This distinguishes them from many other plant groups where the sporophyte is the dominant life stage. Bryophytes are often referred to as "amphibians of the plant kingdom" because they require water for sexual reproduction, highlighting their reliance on the gametophyte stage for reproduction.

Cycads are known for their specialized coralloid roots, which harbor symbiotic cyanobacteria capable of nitrogen fixation. This symbiotic relationship allows cycads to thrive in nitrogen-poor soils, as the cyanobacteria convert atmospheric nitrogen into a form that the plants can use. This mutualistic interaction is crucial for the nutrient uptake of cycads, making the reason a correct explanation for the assertion.

Agar-agar, extracted from species of red algae such as Gelidium and Gracilaria, is used as a solidifying agent in culture mediums. This makes it invaluable in microbiological work for growing bacterial cultures, as it provides a stable and nutrient-rich environment for the bacteria to grow.

It's true that algae contribute significantly to global photosynthesis, thanks in part to their abundance in aquatic environments, where they play a key role in carbon fixation. While algae do possess a diverse array of photosynthetic pigments allowing them to efficiently capture light energy, the primary reason for their substantial contribution to Earth's photosynthesis is their vast numbers and widespread distribution, especially in the oceans. Therefore, while both statements are true, the reason given is not the direct explanation for the assertion.