Answer:
The human skull consists of 22 bones (or 29, including the inner ear bones and hyoid bone) which are mostly connected together by ossified joints, so called sutures. The skull is divided into the braincase (neurocranium) and the facial skeleton (viscerocranium). Its main task is the protection of the most important organ in the human body: the brain.
The brain is almost entirely enclosed by the neurocranium with the exception of the foramen magnum and other foramina at the skull base which serve as entry and exit point for blood vessels and cranial nerves. Also, the skull provides support for all of the facial structures.
Answer: Two analogous structures are similar in phenotype and developed to perform the same function, despite not being inherited from a common ancestor. As so unrelated species may look related due to having analogous structures.
Explanation:
Endocytosis is the process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane, and bringing it into the cell. Exocytosis describes the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell. The main similarity is that both exocytosis and endocytosis are involved in transporting big molecules across the membrane using a vesicle and needs energy. The basic differences are that : 1) Endocytosis brings materials to the inside of the cell while exocytosis takes them out. Exocytosis, on the other hand, is described as the process of fusing vesicles with the plasma membrane to release their contents to the external environment of the cell.
Answer:
Replicated chromosomes at metaphase I = 66
Sister chromatids at metaphase I = 66 x 2 = 132
Sister chromatids at prophase II = 66
Chromosomes in each sperm cells = 33
Explanation:
Metaphase I of meiosis I would have 66 replicated chromosomes in the testicular cells of the bird. Each of the replicated chromosomes would have two sister chromatids. So, a total of 66 replicated chromosomes would have 66 x 2 = 132 sister chromatids.
Due to segregation of homologous chromosomes towards opposite poles in anaphase I, each daughter cell formed by the end of meiosis I would have 33 replicated chromosomes. So, each of the daughter cells would have a total 33 x 2 = 66 sister chromatids at prophase II.
Since meiosis II maintains the chromosome number, each sperm cell formed by the end of meiosis II would have 33 chromosomes.
