The most recent common ancestor of all land plants was probably similar to modern- day members of which group?
A) green algae
B) red algae
C) charophytes
D) brown algae
E) angiosperms
C
The structural integrity of bacteria is to peptidoglycan as the structural integrity of plant
spores is to
A) lignin.
B) cellulose.
C) secondary compounds.
D) sporopollenin.
D
Which kind of plant tissue should lack phragmoplasts?
A) bryophyte tissues
B) diploid tissues of charophytes
C) spore- producing tissues of all land plants
D) tissues performing nuclear division without intervening cytokineses
E) the meristematic tissues of fern gametophytes
The Correct Answer and Explanation is :
Question 1:
The most recent common ancestor of all land plants was probably similar to modern-day members of which group?
Answer: C) charophytes
Explanation:
Charophytes are a group of green algae that share a close evolutionary relationship with land plants (embryophytes). Phylogenetic and molecular studies strongly support the idea that charophytes are the closest living relatives of land plants. Both charophytes and land plants share several key traits, such as the presence of sporopollenin (a durable polymer that prevents desiccation), similar chlorophyll pigments (chlorophyll a and b), and a cellulose-rich cell wall. Additionally, features like the phragmoplast (a structure involved in cell division) and plasmodesmata (intercellular connections) are shared between charophytes and land plants, indicating a common ancestry. Red algae, brown algae, and other algal groups lack these specific characteristics, making charophytes the best match for the ancestor of land plants.
Question 2:
The structural integrity of bacteria is to peptidoglycan as the structural integrity of plant spores is to:
Answer: D) sporopollenin
Explanation:
Peptidoglycan is a polymer that provides rigidity to bacterial cell walls, allowing them to maintain their shape and survive in various environments. Similarly, sporopollenin is a highly durable polymer that provides structural integrity and protection to plant spores and pollen grains. It prevents desiccation and protects against environmental stressors such as UV radiation. Sporopollenin’s chemical stability is crucial for the survival and dispersal of spores in terrestrial environments, analogous to how peptidoglycan ensures bacterial survival. While cellulose and lignin are important structural components of plant tissues, they are not specific to spores. Secondary compounds, while biologically significant, do not play a direct role in the structural integrity of spores.
Question 3:
Which kind of plant tissue should lack phragmoplasts?
Answer: D) tissues performing nuclear division without intervening cytokinesis
Explanation:
The phragmoplast is a structure that forms during cell division in land plants and some green algae (e.g., charophytes). It facilitates the formation of the cell plate, which eventually develops into a new cell wall, ensuring complete cytokinesis. Tissues performing nuclear division without cytokinesis (such as coenocytic or multinucleated tissues) do not undergo complete cell division; thus, they lack phragmoplasts. For example, certain algal and fungal tissues exhibit this type of growth where nuclei divide but the cytoplasm does not, resulting in multinucleated cells. In contrast, bryophyte tissues, spore-producing tissues, and meristematic tissues of ferns involve complete cell division and require phragmoplasts during cytokinesis. Hence, tissues with nuclear division but no cytokinesis lack phragmoplasts.