Pituitary dwarfism is caused by problems arising from the pituitary gland. The pituitary gland, also called the hypophysis, is a gland at the base of the brain that produces many different hormones. This gland is divided into the anterior (front) and posterior (back) halves. The anterior pituitary produces six hormones: growth hormone, adrenocorticotropin (corticotropin), thyroid stimulating hormone (thyrotropin), prolactin, follicle stimulating hormone, and lutenizing hormone. The posterior pituitary gland only produces two hormones: antidiuretic hormone (vasopressin) and oxytocin.
The growth process begins in the lower part of the forebrain in a small organ called the hypothalamus. The hypothalamus releases hormones that regulate the production of other hormones. When the hypothalamus releases growth hormone-releasing hormone (GHRH), the anterior pituitary is stimulated to release growth hormone (GH). Growth hormone then acts on the liver and other tissues and stimulates them to secrete insulin-like growth factor-1 (IGF-1). IGF-1 directly promotes the development of bone and muscle, causing bones to grow in length, and muscles to increase protein synthesis (make more protein).
Since growth is a complex phenomenon, it may be slowed down or stopped by abnormalities arising at any point in the process. Thus, dwarfism can result if there is a deficiency in any of these hormones, if there is a failure in the receptor cells receiving the hormonal stimuli, or if the target cells are unable to respond.
At its most basic, pituitary dwarfism results from decreased production of hormones by the anterior pituitary. When none of the hormones of the anterior pituitary are adequately produced, this is called panhypopituitarism. A common form of pituitary dwarfism is due to deficiencies in the production of growth hormone (GH). When less GH than normal is produced during childhood, an individual's arms, legs, and other structures continue to develop in normal proportions, but at a decreased rate.
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Answer:
The correct answer is b. actors have to be more likely to carry the altruistic allele than non actors.
Explanation:
Altruism is the behavior by an organism that benefits other organisms by costing its own fitness. The actor is the individual who is doing altruism and the recipient is the individual who is getting benefited by the actor's altruism.
An example of altruistic behavior can be seen in animal kingdom easily. Vampire bats give blood to those members of the community who were not able to go for search for blood show altruistic behavior.
Actors have altruistic genes that suggest them to behave altruistically. Non-actors may not contain alleles of altruism but the recipient might have altruistic alleles.
Hamilton's rule says that natural selection will favor the altruistic allele when rb > c.
where r = coefficient of relatedness between donor and recipient
b = benefit received by recipient and
c = cost paid by altruist.
Therefore, the correct answer is b.
Answer:
1. Remove a green leaf from the plant
2. Boil the leaf in boiling <u>water stop enzymatic reaction within cells in leaf</u>
3. Put the boiled leaf in boiling tube containing alcohol <u>extract (ethanol) chlorophyll ethanol dissolves Lipids in cell membranes.</u>
4. Return to leave to the hot water <u>soften the leaf and allows penetration of </u><u> </u><u>i</u><u>odine</u>
5. Remove leaf and perform the iodine test
Explanation:
<em>starch is white powdery substance consisting of glucose which is used by plants as food the percents of starch in leaves evidence enough of the process a photosynthesis being carried out in leaves as the formation of starch necessitates photosynthesis</em>.
I hope this helps :)
Answer: False
Explanation:
Protozoans are not the organism that fix nitrogen for the plants. The organism that fix nitrogen to convert it into a form which can be used by plants are known as diazotrophs.
These are bacteria and archae that fix nitrogen gas found in the atmosphere into more usable form such as ammonia.
These organism can grow without any external source of fixed nitrogen. Example: Rhizobia and azospirillium.
