Answer:
b) Channel pumps
Explanation:
The channels are the transmembrane proteins that serve in the passive transport of substances down the concentration gradient. The channels can be gated or non-gated. The gated channels are opened and closed in response to certain stimuli such as electrical change.
For example, aquaporins are the gated water channels that transport the water across the plasma membrane. The process is driven by the osmotic gradient and does not use the energy of ATP.
Answer:
Why is healthy skin important? Healthy skin is important because it is your first line of defense against bacteria and other pollutants in the environment. Healthy skin is more resilient when faced with external stresses, serves as an important sensory organ and helps to regulate our body temperature.
The outermost layer of skin, called the epidermis, produces a thin barrier layer called the stratum corneum. This layer varies throughout the body in its structure, thickness, composition and functional properties. For example, the skin on your palms and soles is thicker than on your face.
Skin changes such as wrinkling are one of the physical alterations most readily associated with aging. It may surprise you that the outer layer of the skin, the stratum corneum, changes very little as we age. The main changes occur at a deeper level. Collagen, a basic chemical building block of skin and connective tissue, decreases with age.
Explanation:
Explanation:
cAMP binds to protein kinase A and activates it, allowing PKA to phosphorylate downstream factors to produce a cellular response. cAMP signaling is turned off by enzymes called phosphodiesterases, which break the ring of cAMP and turn it into adenosine monophosphate (AMP).
Answer: D). Primary species have large numbers of offsprings, and climax communities contain species that have small numbers of offsprings.
An ecological succession is a process of gradual changes occurs in a biological community with respect to changes in the non-living abiotic factors (water, air and sunlight) and with respect to time until the ecosystem attains stability. Primary or pioneer species are the species which invade the previously barren and primitive landmass for their survival. These species make the environment suitable for the growth of other species. These grow and develop in the initial stages of succession. These species are simple organisms which reproduce asexually and produces large number of offsprings. Examples are lichen and moss. Lichen grows on the surface of rocks and acids released by them causes withering of rocks into soil which facilitate the growth of mosses and other plants. Climax community develops in an ecosystem after replacing many previously inhabiting species. Climax community develops in the end of the ecological succession. It contains species which are highly complex and uses sexual reproduction for the production of offsprings which are less in number as compared to those produced by pioneer species by asexual reproduction.
