Sexual Reproduction in Humans
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Questions and Answers

What is the primary role of the prostate gland in the male reproductive system?

To produce fluid called semen that provides nutrients for sperm cells.

Describe the function of the sperm duct in the male reproductive system.

The sperm duct carries sperm and mixes it with fluids produced by glands before ejaculation.

What dual purpose does the urethra serve in males?

The urethra carries urine from the bladder and semen during ejaculation.

What are the two main functions of the testes in the male reproductive system?

<p>To produce sperm and testosterone.</p> Signup and view all the answers

Why is the scrotum important for sperm production?

<p>The scrotum keeps the testes at a temperature slightly lower than body temperature.</p> Signup and view all the answers

What is the main function of the penis in the male reproductive system?

<p>To pass urine out of the body and allow semen to enter the vagina during intercourse.</p> Signup and view all the answers

What role does the sperm duct play before ejaculation occurs?

<p>It mixes sperm with fluids produced by glands.</p> Signup and view all the answers

How does the presence of testosterone influence the male reproductive system?

<p>Testosterone regulates the development of male reproductive tissues and secondary sexual characteristics.</p> Signup and view all the answers

What is the role of the placenta in terms of nutrient and waste exchange between the mother and fetus?

<p>The placenta facilitates the exchange of nutrients like glucose and oxygen to the fetus, while also removing waste products such as carbon dioxide and urea.</p> Signup and view all the answers

Explain how the structure of the placenta supports its function in diffusion.

<p>The placenta has a large surface area and a thin wall, which optimize it for efficient diffusion of molecules between the mother and fetus.</p> Signup and view all the answers

Why are certain toxins and viruses able to cross the placenta, while others are not?

<p>The ability of toxins and viruses to cross the placenta primarily depends on the size of the molecules; smaller molecules can pass through more easily.</p> Signup and view all the answers

What health complications can arise in a fetus due to the transmission of the rubella virus across the placenta?

<p>Rubella can cause serious health issues such as deafness, heart disease, and eye problems in the fetus.</p> Signup and view all the answers

How can smoking during pregnancy affect fetal health in relation to the placenta?

<p>Smoking can introduce harmful substances like nicotine that may cross the placenta, potentially harming the developing fetus.</p> Signup and view all the answers

What are some physical changes that occur in boys during puberty?

<p>Growth of penis and testes, facial and body hair, muscle development, and voice breaking.</p> Signup and view all the answers

At what age does the average menstrual cycle start for girls?

<p>Around age 12.</p> Signup and view all the answers

What triggers ovulation in the menstrual cycle?

<p>The peak in oestrogen levels that occurs just before day 14.</p> Signup and view all the answers

What happens to the uterine lining if an egg is not fertilized?

<p>The uterine lining breaks down, leading to menstruation.</p> Signup and view all the answers

How long does the average menstrual cycle last?

<p>About 28 days.</p> Signup and view all the answers

What role do hormones from the ovary and pituitary gland play in the menstrual cycle?

<p>They control the menstrual cycle by regulating oestrogen and progesterone levels.</p> Signup and view all the answers

What emotional changes might occur during puberty?

<p>Increased interest in sex and mood swings.</p> Signup and view all the answers

How long does menstruation typically last?

<p>Around 5 to 7 days.</p> Signup and view all the answers

What adaptive feature allows sperm to swim to the egg?

<p>The sperm has a flagellum (tail) that enables it to swim to the egg.</p> Signup and view all the answers

What role do enzymes in the acrosome of sperm play during fertilization?

<p>The enzymes help digest through the jelly coat and cell membrane of the egg when the sperm meets the egg.</p> Signup and view all the answers

Why are mitochondria important for sperm function?

<p>Mitochondria provide energy from respiration for the flagellum to move back and forth for locomotion.</p> Signup and view all the answers

What is the function of the cytoplasm in the egg cell?

<p>The cytoplasm contains a store of energy that provides resources for the dividing zygote after fertilization.</p> Signup and view all the answers

How does the jelly-like coating of the egg cell protect it after fertilization?

<p>The coating changes to form an impenetrable barrier that prevents other sperm nuclei from entering the egg cell.</p> Signup and view all the answers

Compare the size of sperm and egg gametes.

<p>Sperm are very small (45µm), while eggs are larger (0.2mm).</p> Signup and view all the answers

What is the main structural difference between sperm and egg gametes?

<p>Sperm have a head region and flagellum with many structural adaptations, while eggs have a round cell covered in a jelly coating.</p> Signup and view all the answers

How frequently are sperm produced compared to eggs in females?

<p>Sperm are produced every day in huge numbers (around 100 million), while females have thousands of immature eggs but only release one each month.</p> Signup and view all the answers

What hormone is primarily responsible for egg maturation in the ovary?

<p>Follicle-stimulating hormone (FSH)</p> Signup and view all the answers

What occurs when oestrogen levels reach their peak in the menstrual cycle?

<p>LH is released, causing ovulation.</p> Signup and view all the answers

How does progesterone affect the uterine lining?

<p>Progesterone maintains the thickness of the uterine lining.</p> Signup and view all the answers

What happens to the uterine lining when progesterone levels fall?

<p>The uterine lining breaks down, leading to menstruation.</p> Signup and view all the answers

What triggers the release of oestrogen during the menstrual cycle?

<p>FSH stimulates the ovaries to produce oestrogen.</p> Signup and view all the answers

Explain the role of LH in the menstrual cycle.

<p>LH causes ovulation and stimulates the production of progesterone.</p> Signup and view all the answers

During what days does oestrogen peak in the menstrual cycle?

<p>Oestrogen peaks just before day 14.</p> Signup and view all the answers

What are the consequences of rising levels of FSH?

<p>They lead to egg maturation and increased oestrogen release.</p> Signup and view all the answers

What is the role of FSH in the menstrual cycle?

<p>FSH stimulates the development of a follicle in the ovary, leading to egg development.</p> Signup and view all the answers

How does oestrogen affect the uterine lining?

<p>Oestrogen promotes the growth and repair of the uterus lining.</p> Signup and view all the answers

What happens to progesterone levels if fertilization does not occur?

<p>Progesterone levels drop, leading to the breakdown of the uterine lining and menstruation.</p> Signup and view all the answers

What triggers the release of LH during the menstrual cycle?

<p>A high enough level of oestrogen stimulates the release of LH from the pituitary gland.</p> Signup and view all the answers

What does the corpus luteum produce after ovulation?

<p>The corpus luteum produces progesterone.</p> Signup and view all the answers

What is the consequence of a drop in progesterone during the menstrual cycle?

<p>The uterine lining breaks down, resulting in menstruation.</p> Signup and view all the answers

What role does progesterone play during pregnancy?

<p>Progesterone maintains the uterine lining and prevents its breakdown until the placenta develops.</p> Signup and view all the answers

How do hormonal interactions regulate the menstrual cycle?

<p>The interactions between FSH, oestrogen, LH, and progesterone control follicle development, ovulation, and the maintenance of uterine lining.</p> Signup and view all the answers

Flashcards

What is the role of the prostate gland?

The prostate gland produces a fluid called semen which nourishes the sperm cells.

What is the function of the sperm duct?

The sperm duct is a tube where sperm cells travel through to mix with fluids from glands before being released during ejaculation.

What does the urethra carry?

The urethra carries urine from the bladder and semen during ejaculation. A muscular ring stops these fluids from mixing.

What are the two main functions of the testes?

The testes produce sperm cells (male gametes) and testosterone (a male hormone).

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Why are the testes located outside the body in the scrotum?

The scrotum helps keep the testes at a slightly lower temperature than body temperature, which is optimal for sperm production.

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What is the function of the penis?

The penis is the organ that carries urine out of the body and helps to deposit semen into the vagina during sexual intercourse.

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Why is it important that the temperature in the scrotum is slightly less than body temperature?

This lower temperature is ideal for the production and maintenance of sperm cells. If the temperature is too high, sperm can be damaged and become infertile.

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What is the role of testosterone in the body?

Testosterone is a male hormone that triggers puberty, develops male characteristics, and plays a role in sperm production.

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Sperm Flagellum

A tail-like structure that enables sperm to swim towards the egg cell.

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Sperm Acrosome

A cap-like structure at the head of a sperm cell containing enzymes that break down the outer layers of the egg cell, allowing fertilization.

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Sperm Mitochondria

Organelles within sperm cells that provide energy for the flagellum to move, enabling sperm to swim.

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Egg Jelly Coat

A protective layer surrounding the egg cell that changes after fertilization to prevent further sperm entry.

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Sperm Size

Sperm cells are very small, about 45 micrometers in diameter.

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Egg Size

Egg cells are significantly larger than sperm cells, about 0.2 millimeters in diameter.

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Sperm Motility

Sperm cells are able to move independently using their flagellum.

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Egg Motility

Egg cells are not capable of moving on their own.

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What is the placenta?

The placenta is an organ that develops during pregnancy to allow the transfer of oxygen, nutrients, and waste products between the mother and the fetus.

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How does the placenta work?

The placenta facilitates the exchange of materials between the mother and the fetus through diffusion. Substances move from areas of high concentration to low concentration.

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What are some substances that cross the placenta?

The placenta allows the transfer of essential nutrients like glucose, amino acids, and oxygen to the fetus. It also removes waste products like carbon dioxide and urea.

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Why is it important to avoid toxins during pregnancy?

Some toxins and pathogens can cross the placenta and harm the developing fetus. This is why pregnant women are advised to avoid smoking, alcohol, and other harmful substances.

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What are some viruses that can cross the placenta?

Some viruses, like rubella and HIV, are small enough to cross the placenta and infect the fetus, potentially causing serious health problems.

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What causes ovulation?

Ovulation is triggered by a surge in luteinizing hormone (LH) released from the pituitary gland. This surge occurs after oestrogen levels reach their peak.

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What stimulates the ovaries to release oestrogen?

Follicle-stimulating hormone (FSH) stimulates the ovaries to start releasing oestrogen.

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How does oestrogen affect the uterine lining?

Oestrogen causes the uterine lining to thicken, preparing it for a potential pregnancy.

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How does progesterone affect the uterine lining?

Progesterone maintains the thickened uterine lining. If fertilization doesn't occur, progesterone levels drop, causing the lining to break down and shed (menstruation).

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What happens during the menstrual cycle?

The menstrual cycle is a series of hormonal changes that regulate the development and release of an egg. It involves fluctuations in FSH, LH, oestrogen, and progesterone levels.

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What is the role of the pituitary gland in the menstrual cycle?

The pituitary gland releases FSH and LH, which stimulate the ovaries to produce oestrogen and progesterone, influencing the entire cycle.

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What is the purpose of menstruation?

Menstruation is the shedding of the thickened uterine lining if fertilization doesn't occur. This prepares the body for another potential pregnancy.

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What is the relationship between oestrogen and LH?

Oestrogen levels rise throughout the first half of the menstrual cycle and peak just before ovulation. This peak in oestrogen causes the pituitary gland to release a surge in LH, which triggers ovulation.

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What is the role of oestrogen?

Oestrogen causes the uterine lining to thicken and mature the egg. It's released during the menstrual cycle, peaking right before ovulation.

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What is the function of progesterone?

Progesterone is released after ovulation and helps maintain the thickened uterine lining in preparation for a potential fertilized egg. If no fertilization occurs, progesterone levels drop and menstruation begins.

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What is the relationship between oestrogen and progesterone?

Oestrogen levels peak just before ovulation, stimulating the release of an egg. Progesterone levels rise after ovulation, maintaining the uterine lining for potential implantation if the egg is fertilized.

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How is the menstrual cycle regulated?

The menstrual cycle is regulated by hormones released by the ovary and pituitary gland: Oestrogen and progesterone from the ovary, and follicle stimulating hormone (FSH) and luteinising hormone (LH) from the pituitary.

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What happens during menstruation?

Menstruation occurs when a released egg isn't fertilized. The thickened lining of the uterus breaks down and is shed, resulting in bleeding for around 5-7 days.

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What is ovulation?

Ovulation is the release of a mature egg from the ovary, which then travels down the oviduct to the uterus.

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What is the typical length of the menstrual cycle?

The average menstrual cycle lasts 28 days, with ovulation typically occurring around day 14.

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When does the menstrual cycle start?

The menstrual cycle begins in early adolescence for girls, typically around the age of 12, and continues until menopause.

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What causes the thickening of the uterus lining?

Rising levels of progesterone, released from the corpus luteum after ovulation, cause the thickening of the uterine lining, preparing it for potential implantation of a fertilized egg.

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What happens when progesterone levels drop?

When progesterone levels fall, the uterus lining breaks down and is shed through the vagina, resulting in menstruation or a 'period'.

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What is the role of FSH in the menstrual cycle?

FSH, produced by the pituitary gland, stimulates the development of a follicle in the ovary, containing an egg.

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What effect does oestrogen have on the uterus lining?

Oestrogen, produced by the growing follicle, promotes the growth and repair of the uterus lining, making it thicker and more receptive to a fertilized egg.

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How does oestrogen influence FSH production?

Oestrogen, as it reaches a high level, inhibits the production of FSH, preventing the development of multiple follicles.

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What triggers ovulation?

A surge in LH, triggered by high oestrogen levels, causes ovulation, where the mature egg is released from the follicle in the ovary.

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What happens to the follicle after ovulation?

The follicle transforms into the corpus luteum, which starts producing progesterone, crucial for maintaining the uterine lining.

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How does the corpus luteum contribute to pregnancy?

If fertilisation occurs, the corpus luteum continues producing progesterone, preventing the breakdown of the uterine lining, crucial for maintaining pregnancy.

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Study Notes

Sexual Reproduction in Humans

  • Human reproduction involves sexual reproduction, characterized by the fusion of male and female gametes.
  • Key structures and functions of the male reproductive system are detailed, alongside the functions of each part.
  • Detailed breakdown of the female reproductive system and function of each part
  • Gametes (sperm and egg) and their adaptations for fertilization and development are presented.
  • The fertilization process, occurring in the oviducts, and the subsequent development of a zygote are explained.
  • The development of the zygote into an embryo and then a fetus within the uterus is outlined.
  • The role of the placenta in providing nourishment and removing waste for the developing fetus is elaborated.
  • The process of virus transmission across the placenta, concerning various factors like concentration gradients and barrier function, is covered.
  • Key hormones, such as oestrogen and testosterone, and their effects on secondary sexual characteristics are described.
  • The menstrual cycle, including hormonal control, changes in the uterine lining, and the role of FSH and LH, are detailed.
  • Diagrams of the systems and processes are included.
  • Important stages of the menstrual cycle, including menstruation, ovulation, and uterine lining changes, are described.
  • The interaction between all four hormones is discussed.

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Cambridge O Level Biology PDF

Description

Explore the intricacies of human sexual reproduction in this quiz. Learn about the male and female reproductive systems, the processes of fertilization and embryonic development, and the role of the placenta. Test your knowledge on key hormones and mechanisms involved in human reproduction.

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