Answer:
They act to regulate the expression of specific genes (androgen-responsive)
Explanation:
Testosterone is a reproductive hormone in male humans. Testosterone as well as its closely related hormones e.g dihydrotestosterone, all belong to a class of hormones called "Androgens".
Androgens operate by entering into a cell and binds with specific androgen-receptor proteins (AR proteins). This contact activates the AR proteins, forming an androgen-receptor complex.
This complex then translocates into the nucleus of specific cells to bind to the DNA. Once it binds, it either inhibits or promotes the expression of specific genes (androgen-responsive). Hence, AR proteins are transcription factors because they play a significant role in regulating transcription of specific genes i.e. turning 'on' or 'off' of specific genes.
This process helps to direct the development of male sexual characteristics.
Answer: (c) skeleton
Explanation: The musculoskeletal system is made up of the body's bones (the skeleton), muscles, cartilage, tendons, ligaments, joints, and other connective tissue that supports and binds tissues and organs together.
Answer:
Natural selection
Explanation:
Microevolution refers to changes produced at a lower level than species. In genetics, microevolution is the change in the allelic frequency perceptible in a few generations. Most of these naturally produced changes by mutation, natural selection, genetic flux, genetic drift.
After the drought on Daphne Major, many of the plants producing small-sized seeds decreased their reproductive rate drastically. Consequently, there were almost no seeds available for the medium ground finch to feed. The population of this species also decreased to only a hundred birds over two years. Weather conditions and food availability influenced the survival of the animals.
With time, the finched population increased again, but now, the average size of the beaks was larger. The trait modification was related to the availability of only larger seeds with thick husks.
Eating large seeds with medium or small-sized beaks was impossible, so Finches needed to adapt, developing larger beaks to crack open the husks and eat the contents of the seeds.
<u>Natural selection was responsible for the rapid change in the finches´ population beaks size after the drought. </u>The evolutive force modifies the allelic frequencies, increasing the frequency of genetic variants that expressed the larger beak size and declining the frequency of the alleles that expressed smaller beak size.
