1. The passing of traits from parents to the offsprings (children) is the basis of heredity. Traits are notable features or qualities in a person, such that each individual has a different combination of traits that makes us unique from others. They are inherited from our parents and passed from generation to generation. That is to our children, then our children to their children and so on.
2. Our genes encode the instructions that define our traits. Traits are majorly defined by the instructions encoded in the genes. However, environment may influences the traits and may play an important role in shaping the traits we posses. Often times these traits may be changed by the environmental factors.
3. Each of us has thousands of genes, which are made of DNA molecules and reside in our chromosomes. Genes are functional or fundamental units of heredity. They are made up of DNA molecules, and act as instructions to make proteins, through a process of transcription and translation. Transcription involves formation of a messenger RNA which then undergoes translation in the cytoplasm to make proteins.The protein formed determine the traits of an individual.
4. In addition to our genes, the Environment we live in also helps define our traits. The expression of genes in organisms may be influenced by environmental factors, these includes the external factors where the organism lives or develops, and also the internal factors such as its hormones and metabolism.
5. Human have two complete sets of 23 chromosomes. A human being has a total of 46 chromosomes (23×2 = 46). This is referred to as a diploid number (2n). Each set is considered to be a one homologous chromosome set. This is the case of of the somatic cells or the body cells which represents a diploid number of chromosomes.
6. When parents conceive a child, each parent contributes one set of chromosomes.This enhances the passing of traits or genes to the child. The egg cell or the ovum from the mother and the sperm cell from the father contain the haploid number (n) or one set of chromosome. During conception the two combines/fuse to form a zygote which is now diploid (2n).
7. Every child receives half of its chromosomes from the mother and another half from the father. During meiosis in the gametes for both mother and father a haploid cell is formed with one set of chromosomes (haploid, n). Therefore, each child contains half number of chromosomes from the mother and the other half from the father making up the diploid number (2n).
8. This transfer takes place at conception, when the father's sperm joins the mother's egg. During conception, fertilization takes place and the sperm cell fuses with the mother cell (ovum) forming a single cell called Zygote. The zygote has the two sets of chromosomes (23 +23 = 46). The cells then divide by mitosis leading to the development of a child.
9. While most cells in our bodies have two sets of chromosomes, or a total of 46 chromosomes, egg and sperm each have 23 chromosomes. The body cells (somatic cells) contain two sets of chromosomes (diploid number, 2n) from mitosis, while the gametes have a single set of chromosomes (haploid, n), from meiosis.
Answer:
In a habitat there are red bugs and green bugs. The birds prefer the taste of the red bugs, so soon there are many green bugs and few red bugs. The green bugs reproduce and make more green bugs and eventually there are no more red bugs.
Iodized salts helps to prevent an inadequate production of thyroid hormones .
<h3>What is iodized salts ?</h3>
Iodized salt is a table salt . it is a mixture of very little amount of sodium iodide and potassium iodide .
It helps to prevent iodine deficiency .
It is a micronutrient and dietary mineral that is naturally present in the food supply .and also it is a heavy element .generally found near sea coasts .
Iodine deficiency disease includes hypothyroidism .
<h3>What is hypothyroidism ?</h3>
It occurs due to less secretion of thyroid hormone caused by iodine deficiency .it causes stunted growth . it shows low rate of metabolism .
Hypothyroidism includes diseases like myxoedema or gull's disease , cretinism .
Inadequate supply of iodine in diet causes enlargement of the gland known as simple goitre.
<h3>Thyroid hormones :</h3>
It is secreted by endocrine glands known as thyroid gland . it includes two types of hormones known as thyroxine and calcitonin .
Thyroxine is an iodine containing hormone known as tetra-iodothyroxine(80%) and tri-iodothyroxine (20%).
calcitonin is secreted from thyroid gland and is polypeptide hormone .
Learn more about thyroid hormones here:
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The process of
prenatal development occurs in three main stages and they are listed in order;
<span>1. </span>Germinal Stage - begins at conception when the
sperm and egg cell joined in one of the two fallopian tubes.
<span>2. </span>Embryonic Stage - begins at the beginning of
the third week after conception. This stage plays an important role in the
development of the brain.
<span>3. </span>Fetal Stage - begins during the ninth week
and lasts until birth.
Answer:
Option C - The sympatric salamander populations evolved their present body sizes after they became sympatric.
Explanation:
First, note the definitions of each terms.
1) Sympatric occurs when organisms especially of same species occurring in the same, or in overlapping territory, do not interbreed.
2) Allopatric occurs when organisms are NOT living in the same territory and thus unable to crossbreed.
On 1st QUESTION
The argument would be strengthened by the failure of P. cinereus and P. hoffmani to crossbreed making traits for body size to become distinct (dissimilar) in each specie.
On 2nd QUESTION
Definitely, salamanders species occurring in the territory, do not interbreed after they became sympatric, thus, making characters among same species to be increasingly different over generations.