IGCSE Biology Paper-2: Specimen Questions with Answers 122 - 123 of 203

Question 122

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Question

MCQ▾

The graph shows a hormone that is involved in regulation the human female menstrual cycle.

The human female menstrual cycle

The Human Female Menstrual Cycle

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Which hormone is shown by the curve?

Choices

Choice (4)
a.LH
b.Estrogen
c.Progesterone
d.FSH

Answer

c.

Explanation

  • Progesterone prepares the endometrium for the potential of pregnancy after ovulation. It triggers the lining to thicken to accept a fertilized egg. It also prohibits the muscle contractions in the uterus that would cause the body to reject an egg. While the body is producing high levels of progesterone, the body will not ovulate.
  • If the woman does not become pregnant, the corpus luteum breaks down, lowering the progesterone levels in the body. This change sparks menstruation. If the body does conceive, progesterone continues to stimulate the body to provide the blood vessels in the endometrium that will feed the growing fetus. The hormone also prepares the limit of the uterus further so it can accept the fertilized egg.
Progesterone prepares

Progesterone Prepares

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Question 123

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Question

MCQ▾

The diagram shows a section through a flower.

The diagram shows a section through a flower

The Diagram Shows a Section through a Flower

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Where is the site of pollen development?

Choices

Choice (4)
a.Diagram D
b.Diagram A
c.Diagram B
d.Diagram C

Answer

b.

Explanation

Stamen

  • Stamen is the male reproductive unit of angiosperms.
  • Stamen consists of anther, connective, and filament.
  • The long and slender stalk called as fi lament and the terminal structure is known as anther.
  • Typically, angiospermic anther is bilobed which is connected by connective and dithecous i. e. , each lobe has two theca. The bilobed structure of the anther is tetrasporangiate (four sporangia). In transverse section, it appears as four sided tetragonal structure consisting of two microsporangia in each lobe.
  • Microsporangia develop into pollen sac filled with pollen grains.
  • The number, form, and length of stamen vary from species to species.
The diagram shows a section through a flower

The Diagram Shows a Section through a Flower

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