The statement about blood that is true is that the blood is about 92 percent water.
Blood is about 92 percent water. This means that most of its mass is composed of water, and that it has a similar chemical makeup as water. Blood is also slightly more acidic than water, with a pH of 7.35-7.45. It is also slightly more viscous than water, meaning it has a thicker consistency. Finally, blood is slightly more salty than seawater. This is due to the presence of electrolytes and other elements in the blood, such as sodium, potassium, and chloride.
Overall, these characteristics of blood provide it with the unique properties it needs to fulfill its purpose in the human body. Water, electrolytes, and other chemicals present in the blood are used to maintain pH balance, provide nutrients to the body, and carry away waste products.
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do not add any more lactose and watch what transpires. note what happens and why this occurs. how could you re-activate the lacz gene?
The lacZ gene is responsible for the enzyme β-galactosidase which breaks down lactose. When no more lactose is added, the lacZ gene is not activated and the β-galactosidase enzyme does not break down lactose. To re-activate the lacZ gene, you would need to add lactose back in so that the β-galactosidase enzyme is activated and lactose is broken down.
Lactose is a disaccharide sugar composed of glucose and galactose, which is found in milk. Lactose can be hydrolyzed into glucose and galactose through the catalytic action of lactase enzymes. This reaction occurs in the small intestine, and the glucose and galactose are then absorbed and used as energy by the body.
When lactose is present, the lac operon is activated, and the genes involved in lactose metabolism are transcribed into messenger RNA. When lactose is absent, the lac operon is turned off, and these genes are not expressed.
To re-activate the lacZ gene, it is necessary to add lactose or a lactose analog such as IPTG to the culture medium. IPTG is an inducer of the lac operon that does not bind to the repressor protein, allowing the genes involved in lactose metabolism to be expressed even in the absence of lactose.
When lactose is present, the lac operon is activated, and the genes involved in lactose metabolism are transcribed into messenger RNA. When lactose is absent, the lac operon is turned off, and these genes are not expressed.
Therefore, if no more lactose is added to the culture medium, the lac operon will turn off, and the genes involved in lactose metabolism will not be expressed. This occurs because the repressor protein binds to the operator site of the operon, preventing RNA polymerase from transcribing the genes involved in lactose metabolism.
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hich gas began to increase in the atmosphere as a result of photosynthesis by autotrophic prokaryotes approximately 2.7 billion years ago?
Oxygen began to increase in the atmosphere as a result of photosynthesis by autotrophic prokaryotes approximately 2.7 billion years ago. This process, called oxygenic photosynthesis, uses energy from sunlight to convert carbon dioxide and water into organic matter (carbohydrates) and oxygen gas. This new source of oxygen led to an increase in atmospheric oxygen, which had previously been low, and allowed for the evolution of more complex forms of life.
Oxygenic photosynthesis is carried out by autotrophic prokaryotes, or “oxygenic phototrophs”, which are organisms that use energy from sunlight to convert inorganic molecules into organic molecules. These phototrophs use light to break down carbon dioxide molecules, and form simple organic molecules, such as glucose. The byproducts of this process are organic molecules and oxygen gas. As a result of this reaction, the amount of oxygen in the atmosphere began to increase.
This increase in oxygen allowed for the evolution of more complex life forms. Before the rise of oxygenic photosynthesis, the atmosphere was largely composed of carbon dioxide and nitrogen, which prevented the evolution of complex organisms. With the rise of oxygen, more complex organisms could thrive, as oxygen allowed for respiration, which is the process of breaking down food molecules to create energy. As a result, the diversity of organisms increased and eventually led to the evolution of multicellular organisms.
In conclusion, oxygen began to increase in the atmosphere approximately 2.7 billion years ago as a result of oxygenic photosynthesis carried out by autotrophic prokaryotes. This allowed for the evolution of more complex forms of life and the development of multicellular organisms.
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