The first line of defence (or outside defence system) includes physical and chemical barriers that are always ready and prepared to defend the body from infection. These include your skin, tears, mucus, cilia, stomach acid, urine flow, 'friendly' bacteria and white blood cells called neutrophils.
The answer would be B. Atom, star, galaxy, universe.
Explanation: atoms are small cells that make up everything in existence. They're too small to be seen by the naked human eye. Stars are big balls of gas that can be seen at night in the sky. These are second biggest because you can see these with the naked eye, but galaxies you can not. The galaxy holds the earth, all of the other planets, stars, and other things. If the galaxy can hold all of that then clearly it would be bigger than the stars. The universe is what holds our galaxy. There are millions of other galaxies out there in the universe. Ours is just a small one of an infinite number.
Answer:
Explanation:
The rate limiting reaction of aerobic respiration involves the phosphorylation of fructose phosphate by the enzyme phosphofructokinase. The rate at which this enzyme makes product is [increased, decreased] when ATP levels rise because the molecule ATP binds to an allosteric site on the enzyme and acts as a direct inhibitor. When ATP levels fall AMP binds to the allosteric site of phosphofructokinase. This interaction leads to an increase of cellular ATP, so that this is an example of a negative feedback loop.
Answer: B
Explanation: Most mammals have only one pair of sex chromosomes in each cell. Males have only one Y chromosome and one X chromosome, while females have two X chromosomes. In Mammals, the Y chromosome contains a gene, SRY, which triggers embryonic development in a male.
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