<h2>Scurvy </h2>
Explanation:
(a) Collagen is the major structural component of cartilage,bones and tendons
- The basic unit of collagen is tropocollagen and each tropocollagen consists of three coiled left handed polypeptide chains called α chains
- Generally each α chain consists of a repeating tripeptide sequence called: G-X-Y
- Here G represents glycine; X represents proline and Y represents hydroxyproline
- Rigidity of collagen molecule is due to presence of proline and hydroxyproline
- Hydroxylation of proline is catalysed by prolyl hydroxylase enzyme which use ascorbate,α ketoglutarate and oxygen
- α ketoglutarate is oxidatively decarboxylated to form carbon dioxide and succinate
- Sequence of events leading from a dietary vitamin C deficiency to symptoms such as bruising and breakdown of supporting tissues includes: tissue levels of ascorbic acid is low; enzyme prolyl hydroxylase is inactive; proline is not hydroxylated; the triple helix is inadequately stabilized; collagen breaks down; defects in tissues that depend on collagen
; tissues that depend on collagen are subject to breakdown and bruising
(b) Sailors are no longer susceptible to scurvy because fresh fruits which are the source of vitamin C source are available now
British sailors called "limeys" to this day,this term reflects the British navy's use of limes
Answer: Decomposers plan an important role in the biogeochemical cycling for nutrients in the environment as they are responsible for the breakdown and return of nutrients back to the environment in their native state.
Answer:
More info given below.
Explanation:
This attraction occurs as a result of static charge. You see an atom is referred to as the smallest particle of a substance; and when an atom gains or looses electrons it becomes unstable creating a difference in potential. However in this case rubbing induces friction which induces heat. This heat excites the atom to loose electrons creating a negative charge on the silk and a converse positive charge on the pencil.
<h3><u>Answer;</u></h3>
Compressions
Rarefactions
<h3><u>Explanations;</u></h3>
- A wave is a transmission of a disturbance from one point to another, and involve the transfer of energy from the source to another point.
- Waves may be classified as longitudinal waves or transverse wave depending on the vibration of particles relative to the wave motion or mechanical and electromagnetic waves based on the material medium of transmission.
- <em><u>Sound waves are examples of longitudinal waves that are mechanical waves since they require material medium for transmission. Longitudinal waves involves transmission of waves such that the vibration of particles is parallel to the wave motion , creating compressions and rarefactions.</u></em>
Calcium levels in the body are maintained by hormones. If the blood calcium level rises above a set point, calcitonin is secreted by the thyroid gland and sets into motion responses to lower the blood calcium back to the set point. If the blood calcium level falls below a set point, the parathyroid gland secretes parathyroid hormone that sets into motion responses to raise the blood calcium. These homeostatic responses are examples of:
a. positive feedback
b. effectors
c. sensors
d. negative feedback
Answer:
d. negative feedback
Explanation:
Negative feedback responses are the ones that counteract the change. Any alterations in the internal body conditions such as blood calcium levels are sensed by receptors. The information is sent to the brain which in turn commands the effectors such as endocrine glands to secrete the required hormones to restore the normal conditions. Here, changes in the calcium levels are counteracted by the secretion of calcitonin and parathyroid hormones and the calcium is maintained within a narrow range. This represents negative feedback.
