In large populations, small fluctuations in survivorship or reproduction among individual organisms are unlikely to affect allele or genotype frequencies in the population. a. True
b. False

True.

Explanation:

A population is defined as the set of individuals that inhabit a given geographic area. A population has a certain allele frequency, which is the measure of the relative proportion of alleles in a given population, expressed as a percentage or unit. It is estimate using the number of times the allele is found in a locus and dividing it by the total number of alleles. While the genotypic frequency refers to the number of times that each of the genotypes generated by the two-by-two combinations of the alleles involved in the locus under study appears in relation to the total number of genotypes (which will be equal to the total number of individuals included in the study).

The population can be increased or decreased according to the birth and death rates. Generally, unless specific alterations occur, such as the spread of a disease, immigration, emigration, natural disasters, and others, the size of the population will remain constant. This means that the birth rate is quite similar to the death rate. And the larger the population, the more difficult it is to disturb this balance between births and deaths. So if small fluctuations in survival or reproduction occur between individuals, it is unlikely that this will affect the frequency of alleles and/or genotypes.   This is explained using the Hardy-Weinberg principle states that the genetic composition of a population remains in equilibrium as long as no mutation occurs, and nor natural selection nor any other factor acts. After a generation of random mating, the frequencies of the genotypes of a locus are fixed at an equilibrium value. Then, the genetic variation in a population will remain constant from one generation to the next in the absence of extreme disturbing factors such as those mentioned above (diseases, natural disasters, and others).

Note that for this principle to be fulfilled, the population must be diploid (have two alleles of each gene), must reproduce sexually in a random manner, and must be large enough to minimize the effect of genetic drift (random fluctuations in allele frequencies from one generation to the next, due to random events that can cause certain traits to become dominant or disappear from a population).

synovial joints are characterized by the presence of a joint cavity. the walls of this space are formed by the articular capsule, a fibrous connective tissue structure that is attached to each bone just outside the area of the bone’s articulating surface. the bones of the joint articulate with each other within the joint cavity.

friction between the bones at a synovial joint is prevented by the presence of the articular cartilage, a thin layer of hyaline cartilage that covers the entire articulating surface of each bone. however, unlike at a cartilaginous joint, the articular cartilages of each bone are not continuous with each other. instead, the articular cartilage acts like a teflon® coating over the bone surface, allowing the articulating bones to move smoothly against each other without damaging the underlying bone tissue. lining the inner surface of the articular capsule is a thin synovial membrane. the cells of this membrane secrete synovial fluid (synovia = “a thick fluid”), a thick, slimy fluid that provides lubrication to further reduce friction between the bones of the joint. this fluid also provides nourishment to the articular cartilage, which does not contain blood vessels. the ability of the bones to move smoothly against each other within the joint cavity, and the freedom of joint movement this provides, means that each synovial joint is functionally classified as a diarthrosis.

outside of their articulating surfaces, the bones are connected together by ligaments, which are strong bands of fibrous connective tissue. these strengthen and support the joint by anchoring the bones together and preventing their separation. ligaments allow for normal movements at a joint, but limit the range of these motions, thus preventing excessive or abnormal joint movements. ligaments are classified based on their relationship to the fibrous articular capsule. an extrinsic ligament is located outside of the articular capsule, an intrinsic ligament is fused to or incorporated into the wall of the articular capsule, and an intracapsular ligament is located inside of the articular capsule.

at many synovial joints, additional support is provided by the muscles and their tendons that act across the joint. a tendon is the dense connective tissue structure that attaches a muscle to bone. as forces acting on a joint increase, the body will automatically increase the overall strength of contraction of the muscles crossing that joint, thus allowing the muscle and its tendon to serve as a “dynamic ligament” to resist forces and support the joint. this type of indirect support by muscles is very important at the shoulder joint, for example, where the ligaments are relatively weak.

additional structures associated with synovial joints

a few synovial joints of the body have a fibrocartilage structure located between the articulating bones. this is called an articular disc, which is generally small and oval-shaped, or a meniscus, which is larger and c-shaped. these structures can serve several functions, depending on the specific joint. in some places, an articular disc may act to strongly unite the bones of the joint to each other. examples of this include the articular discs found at the sternoclavicular joint or between the distal ends of the radius and ulna bones. at other synovial joints, the disc can provide shock absorption and cushioning between the bones, which is the function of each meniscus within the knee joint. finally, an articular disc can serve to smooth the movements between the articulating bones, as seen at the temporomandibular joint. some synovial joints also have a fat pad, which can serve as a cushion between the bones.

a chair, a bed, and a toothbrush

explanation: