After two half-lives or 60 years, 7.5 g of the element will be left.
<u>Explanation:</u>
<u>Half-life:</u>
- In simple words, Half-life can be defined as the amount of time needed for a quantity to fall to half its value as contained at the beginning of the time period.
- In this problem the half-life of the element is thirty years, then after thirty years half of the sample would have decayed and half would be left as it is.
- After thirty years (The first half-life ) 30 /2 = 15 g declines and 15 g remains disappeared.
- And after another sixty years (The two half-lives) 15 /2 = 7.5 g declines and 7.5 g remains disappeared.
- After two half-lives or 60 years, 7.5 g of the element will be left.
Answer:
I) Sexual reproduction
II) Mutation
Explanation:
Variations refer to the difference observed within organisms of the same species. Variation are introduced into a population by:
- new genetic combinations that occur during sexual reproduction (i.e during meiosis)
- mutations, spontaneous changes that occur in genes and chromosomes.
Answer:
The correct answer is D. is a facultative anaerobe
Explanation:
A facultative anaerobe is the organisms that can live in the absence of oxygen but prefer to utilize the oxygen when oxygen is present in the environment.
An anaerobic organism requires more amount of energy sources like carbohydrates because they use the fermentation process to make energy and this process results in the formation of less energy than aerobic respiration.
All the bacteria of family Enterobacteriaceae that live in the intestine are facultative anaerobes. Therefore facultative anaerobe can thrive in both the presence and absence of oxygen so the correct answer is D. is a facultative anaerobe.
It will all make more sense if you start from the beginning of the sequence with the structure of DNA. You will remember that messenger RNA contains a sequence of bases which, read three at a time, code for the amino acids used to make protein chains. Each of the sets of three bases is known as a codon.
Answer;
Two recessive alleles are the number of alleles that a person must have to have albinism.
Explanation;
When a trait is recessive, such as albinism, an individual must have two copies of a recessive allele to express that particular trait. Recessive alleles are denoted by a lowercase letter , such as b versus B. Only individuals with a bb genotye will express a recessive trait, hence, the offspring must receive one recessive trait from each parent to exhibit the recessive trait.
