1. when during the cell cycle is a cell’s dna replicated?
a) g1 phase
b) g2 phase
c) s phase
d) m phase

2. which of the following represents the phases of mitosis in their proper sequence? a) prophase, metaphase, anaphase, telophase
b) interphase, prophase, metaphase, anaphase, telophase
c) interphase, prophase, metaphase, telophase
d) prophase, anaphase, metaphase, telophase

The correct answers are-

1) C) S Phase

2) A) prophase, metaphase, anaphase, telophase.

Cell cycle corresponds to the division of cell, which occurs primarily through two phases that are - Interphase ( which has G1, S, and G2 phase) during which cell grows, duplicates its genetic material and M ( mitotic phase) phase during which cell divides.

S phase ( synthesis phase) corresponds to the duplication of the genetic material (DNA). It takes place place after G1 ( Gap 1 phase) phase.

2) Mitosis is a type of cell divison in which one parent cell divides to produce two daughter cells with same number of chromosomes. Prophase is the first phase, followed by metaphase, anpahse, and telophase.

1. I believe the correct answer is C. S Phase.

2. I believe the answer is B. interphase, prophase, metaphase, anaphase and telophase

The cell cycle is divided into 4 stages i.e. the Gap 1 (G1), Gap 2 (G2), Synthesis (S) and Mitosis (M) stage. The M stage is the longest and has 5 further stages that are interphase, prophase, metaphase, anaphase and then telophase. It is during the S phase that DNA is replicated

The cell cycle starts with the G1 stage where the cell rests from a previous cycle and also checks for any errors in the DNA. If none were found, it will proceed to the Synthesis (S) phase. In this phase, the chromosomes enter as single strands but come out as double strand due to replication of DNA. The cell cycle enters the G2 phase where for the last time error checking is done to confirm if any errors are present. If any are present, the cycle is terminated and if not, it proceeds to the Mitosis phase. In the M phase, the cell will undergo extensive cell division which starts with the chromatin condensing in the interphase and the nucleus envelope disappears releasing the chromosome pairs. Pairs of chromosomes then emerge in the prophase and food is stored for the division including doubling of cell organelles. Microtubules form in this stage. The cell then enters the metaphase stage where the chromosome pairs arrange themselves at the equator of the cell and held by the microtubules. The microtubules start to shorten and in the anaphase stage, single strands of chromosome are pulled to different poles of the cell and the microtubules then continue to shorten much more further pulling the single strands more towards the different poles. The cytoplasm then starts to pinch into 2 (cytokinesis) and the different sides start forming different nucleus. IN the end of telophase, 2 daughter cells emerge and the M phase ends concluding the cell cycle. The cell again will go into G1 phase to rest and start the next cycle.

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.