Briefly describe what happens during meiosis 1 and meiosis 2

Answer AND Explanation:

Meiosis consists of two successive divisions which are designated meiosis I and meiosis II. During prophase I, homologous chromosomes lie side by side and become intertwined. The nucleolus disappears and centrioles become arranged at opposite sides of the nucleus. In metaphase I, the homologous chromosomes still associated as bivalents move to the equator of the spindles. They attach to the spindles by their centromeres such that two homologous chromosomes orientate towards opposite poles. In anaphase I, the homologous chromosomes separate from one another and migrate to the opposite poles. In telophase I, when the chromosomes reach their respective poles the cell divides across the middle. The daughter cells may undergo a short interphase before proceeding to meiosis II.

In prophase II, chromosomes become shorter and thicker. A new spindle apparatus is formed. Metaphase II, the chromosomes move to the equator of the spindle and attach to the spindle fibre at their centromeres. The chromosomes orientate themselves towards the opposite poles. Anaphase II, the sister chromatids separate from each other and move to the opposite poles pulled by shortening of the spindle fibres. Telophase II, the spindle apparatus disappears. A new nuclear membrane is formed around each set of chromatids. The chromatids uncoil and the cell divides into two.

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.

question#1

ans:

cell is the basic unit of organization of all living things. cells are often called the building block of life and it is the smallest unit of life. the study of cell is called cell biology. cell consists of cytoplasm enclosed within membrane, which contain bio-molecules such as proteins and nucleic acid.

two third of cell is water, which means that two-third of your whole body is water. the rest is the mixture of molecules, mainly proteins, lipids and carbohydrates.

question#2

ans:

organ:

an organ is a group of tissues specialized to form a functional unit. an example is the heart in animals.

organ system:

an organ system is a group of several organs whose functions are synchronized to release an effective action in a living organism. an example is digestive system.

question#3

different systems perform different function at tissue level. for example, the respiratory system facilitates breathing. in the alveoli tissue of the lungs, the exchange of oxygen and carbon dioxide molecules between the air and the bloodstream occurs by passive transport, so that oxygen is taken in and carbon dioxide and water are removed. different systems of the body carry out different functions. for example, your digestive system is responsible for taking in and processing food, while your respiratory system working with your circulatory system is responsible for taking up oxygen and getting rid of carbon dioxide.

question#4

different systems perform different function at tissue level. for example, the respiratory system facilitates breathing. in the alveoli tissue of the lungs, the exchange of oxygen and carbon dioxide molecules between the air and the bloodstream occurs by passive transport, so that oxygen is taken in and carbon dioxide and water are removed. different systems of the body carry out different functions. for example, your digestive system is responsible for taking in and processing food, while your respiratory system—working with your circulatory system is responsible for taking up oxygen and getting rid of carbon dioxide.

question#5

our body works because of the interactions that happen between organs and organ systems.  

for example:  

the heart to regulate blood flow throughout the body. the blood carries oxygen and nutrients to the cells and carries carbon dioxide and waste away from the cells. body systems work together in maintaining a constant internal environment. when this balance is disrupted, the body systems may not function properly, and human health can suffer.   you start to feel bad.