Answer:
In the first step of meiosis I, the chromosomes/genetic material of the cell condenses into a visible form, into a form called heterochromatin. The nucleolus also disappears.
In the second step, a process called synapsis occurs. This is when homologous chromosomes align themselves, gene by gene.
In the third step, crossing over occurs. Segments of corresponding DNA are cut and exchanged between non-sister chromatids of the formed tetrads.
In the fourth step, the nucleus fragments, the nuclear envelope fragments, the two centrosomes (if we're talking about an animal cell) separate from each other as their asters and mitotic spindles (mostly microtubules (kinetochore and non-kinetochore) lengthen. The microtubules extending from the centrosomes can now connect to chromosomes.
Answer:
Unlike a steady pattern of growth, arthropods exhibit an external growth that proceeds in a sequence of step-like jumps, as the organism builds and replaces its exoskeleton. The arthropod does not grow bigger in size between these jumps. An aquatic arthropod gradually replaces body mass for water detained inside the tissues between molts.
Answer AND Explanation:
As light reflected from an external object enters the eye, it is refracted by the cornea, aqueous humour, the lens and vitreous humour so that an image is focused on the retina. The image is real, upside down and smaller than the object. The photoreceptor cells are stimulated by the reflected light and impulses are set off. The impulses are transmitted by neurons through the optic nerve to the optic region of the brain. The brain interprets the impulse as an upright impression of the object.
Answer:
a shallow recess, especially one in a wall to display a statue or other ornament.
