Exercices S'entraîner
EX
ET
1 Age d'une momie
proportion ratomes de carbone 16 restants
par rapport au nombre d'atomes de carbon
Une momie a été découverte en Egypte dans la vallée des Rois. de départ
On réalise une datation au carbone 14. Cet élément radioactit,
produit en continu dans l'atmosphère terrestre, reste en 08
proportion constante dans les organismes vivants. Le carbone 02
n'étant plus renouvelé à partir du décès. sa proportion
diminue comme l'indique le graphique ci-contre.
On mesure une baisse de 40 % de la proportion de carbone 14
03
de la momie
22
12
0.0
5 000
5000 20000 25000
temps écoule annees
1. Pourquoi le carbone 14 n'est-it plus renouvelé à partir du
décès des êtres vivants?
2. En vous aidant de la coube
cater la momie.
3. Peut-on utiliser la méthode su carbone 14 pour
dater les dinosaures se
555 milions d'an-
nées ? Pourquoi
Prepa
CONTRÔLE CONTINU

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.

the answer would be   10%