IGCSE Biology Paper-4: Specimen Questions with Answers 45 - 47 of 279

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Question 45

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Figure shows a structure of leaf. Label its different parts

Image Shows Cellular Structure of Leaf

Explanation

Cellular Structure of Leaf

Question 46

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Explain is monomer/Polymer cycle of proteins with the help of diagram.

Explanation

Image Showing the Monomer – Polymer Cycle

The monomer – polymer cycle: It is a dehydration and hydrolysis process. In given diagram there are amino acids and protein are shown. The amino acids, which are monomers, are joined together by removal of H2O by dehydration synthesis process and make polymers (protein) . When the protein is no longer required, it degrade by adding back the water molecule by hydrolysis process.

Question 47

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Write the name and functions of Endocrine glands and hormones release from them.

Explanation

Image Shows Name and Functions of Endocrine Glands
Endocrine glandHormoneFunctions
HypothalamusThyrotrophin releasing hormoneStimulates release of thyroid stimulating hormone (TSH)
HypothalamusSomatostatinprevents release of hormones such as growth hormone
HypothalamusGrowth Hormone Releasing Hormone (GHRH)Stimulates release of growth hormone (GH)
Anterior pituitaryThyroid stimulating hormone (TSH)Stimulates release of thyroxin
Anterior pituitaryFollicle stimulating hormone (FSH)Females: promotes development of eggs and follicles in the ovary prior to ovulation Males: promotes production of testosterone from testis
Anterior pituitaryAdrenocortico-trophic hormone (ACTH)Stimulates the adrenal glands to produce mainly cortisol
Posterior pituitaryVasopressin (anti-diuretic hormone, ADH)Acts to maintain blood pressure by causing the kidney to retain fluid and by constricting blood vessels
Posterior pituitaryOxytocinCauses ejection of milk from the milk ducts and causes constriction of the uterus during labor
Thyroid glandThyroxin (T4)regulate the body՚s metabolic rate
Parathyroid glandsParathyroid hormone (PTH)Increases blood calcium levels
PancreasInsulinto lower blood glucose levels
OvaryEstrogensActs to promote development of female primary and secondary sexual characteristics.
TestisTestosteronePromotes the development of male sexual characteristics including sperm development

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