Question

8. Which of the statements about the organization of complex multicellular organisms is false? Only some cells are in direct contact with the environment. Exterior cells receive environmental signals directly, whereas interior cells receive environmental signals indirectly Exterior cells are highly differentiated, whereas interior cells are not differentiated. Interior cells cannot grow as fast as exterior cells without mechanisms to transfer nutrients between cells. Signals transferred from exterior cells to interior cells can activate or repress gene expression in the interior cells. 9. In what types of multicellular organisms do plasmodesmata serve as a mechanism of cell-cell signaling? plants animals fungi those types of organisms that spend only a portion of their life cycle in a multicellular state 10. Which of the statements reflects the evolution of complex multicellularity? Complex multicellularity evolved independently at least six times in different groups of organisms. O Complex multicellularity evolved once in the common ancestor of all eukaryotic organisms. Complex multicellularity evolved independently in prokaryotes and eukaryotes. Complex multicellularity evolved twice: once in the common ancestor of plants and fungi, and once in animals. Simple multicellular organisms evolved from complex multicellular ancestors. 11. Which of the statements is a characteristic of complex multicellularity? Interior cells are exposed to a different physical and chemical environment than exterior cells. All cells are exposed to an exterior surface. The interior cells are more tolerant to lower oxygen levels than exterior cells. All cells of complex multicellular organisms express the same genes.

Answer 1

8. Exterior cells are highly differentiated whereas interior cells are not differentiated.

(This statement is wrong as like exterior cells our interior cells like muscle cells, blood cells are also highly differentiated. our exterior cells like skin cells are directly exposed to the environment and grows much faster in comparison to the other cells of our body. Cells receive and process information from the outside environment for example chemical may bind to the cell receptor and play important role in cell signaling. The interior cells receive signals indirectly)

9. PLANTS

Only plant and algal cells possess plasmodesmata that coordinates develpoment, share resources and helps in cell-cell signaling.

10. Complex multicellularity evolved independently at least six times in different groups of organisms.

(multicellular organisms we know are made up of multiple cells and they arose either by cell division or due to aggregation of cells. It is said that multicellularity in eukaryotes evolved independently about 25 times and complex multicellular organisms evolved only in 6 eukaryotic groups These groups are animals, fungi, brown, red and land plants)

11. Interior cells are exposed to a different physical and chemical environment than exterior cells.

(This statement is true, while other statements are false. All cells in the complex organisms do not express same genes as different genes are either expressed or repressed in different cells of a multicellular oraganism. Second statement is also wrong because our interior cells are not exposed to outside environment and interior cells too require oxygen)