Biology Chapter on Reproduction and Development

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Questions and Answers

What is the role of genetic variation in reproduction?

It has no effect on survival rates.

It decreases the chances of natural selection.

It ensures the reproduction of identical organisms.

It increases the chances of natural selection. (correct)

During which stage does differentiation of cells start?

Zygote

Blastula (correct)

Morula

Fetus

What does the ectoderm develop into?

Skin and nervous system (correct)

Digestive system

Circulatory system

Muscles and excretory system

What significant change occurs by the end of the second trimester?

All major organs have formed. Signup and view all the answers

What does ovoviviparous mean?

Organisms that develop inside the mother but in eggs. Signup and view all the answers

What role does testosterone play in male reproductive development?

It regulates the development of primary and secondary sexual characteristics. Signup and view all the answers

Which of the following describes the difference between internal and external fertilization?

Internal fertilization produces fewer offspring but with a higher survival rate. Signup and view all the answers

What marks the transition from embryo to fetus?

The development of genitalia. Signup and view all the answers

What is one key advantage of sexual reproduction compared to asexual reproduction?

Promotes genetic diversity Signup and view all the answers

During which process do cells move inward in the blastula?

Gastrulation Signup and view all the answers

Which embryonic tissue layer is primarily responsible for the development of the circulatory system?

Mesoderm Signup and view all the answers

Which stage follows the morula in embryonic development?

Blastula Signup and view all the answers

What is the main characteristic of viviparous organisms?

Embryos develop inside the mother Signup and view all the answers

At which week does the embryo transition into the fetal stage?

Eighth week Signup and view all the answers

Which of the following hormones is primarily responsible for regulating sperm production?

FSH Signup and view all the answers

What is a notable change that occurs during the second trimester of pregnancy?

Rapid skeleton formation Signup and view all the answers

What is the primary purpose of extraembryonic membranes?

Protection and waste transport Signup and view all the answers

Which statement is true regarding the roles of GnRH in male reproductive development?

Regulates the pituitary glands Signup and view all the answers

What occurs during the stages of gastrulation in embryonic development?

Cells at one end of the blastula move inward to form layers. Signup and view all the answers

What significant developmental change happens by the seventh week of pregnancy?

The brain and spinal cord begin to form. Signup and view all the answers

Which type of reproductive strategy typically results in a lower survival rate for offspring?

Oviparous Signup and view all the answers

During which trimester do significant changes in the brain occur as the fetus prepares for birth?

Third trimester Signup and view all the answers

What is the role of the mesoderm in embryonic development?

Develops the circulatory system and muscles. Signup and view all the answers

What is one advantage of internal fertilization compared to external fertilization?

Higher success rate of fertilization and increased survival rate. Signup and view all the answers

Which hormone plays a key role in female reproductive development?

Estrogen Signup and view all the answers

What is the function of extraembryonic membranes?

To facilitate transport of nutrients and wastes. Signup and view all the answers

What defines ovoviviparous development?

Embryos develop within the mother's body without a placental connection. Signup and view all the answers

During what stage of development does a zygote first become known as an embryo?

After implantation in the uterus Signup and view all the answers

Study Notes

Reproduction and Development

Organisms reproduce to ensure species survival, transferring genetic information that creates variation, increasing the likelihood of natural selection.
Reproduction types: sexual (two parents) and asexual (more offspring).
Fertilization and Cleavage: Rapid cell division from the zygote, creating a multicellular embryo without significant size increase.
- Stages:
  - Morula (16 cells, in fallopian tube)
  - Blastula (16 cells rearrange to hollow sphere)
  - Differentiation starts in the uterus (Blastocyst). Implantation: Blastocyst attaches to the uterus for nutrients and waste removal.
  - Gastrulation: Inward movement of cells at one blastula end, adding cells to the embryo, sorting into three layers.
- Embryonic Tissue Layers:
  - Ectoderm: Skin and nervous system.
  - Endoderm: Digestive system.
  - Mesoderm: Circulatory system, muscles, and excretory system.
Embryo Development:
- First trimester (zygote to embryo): Brain and spinal cord formation. Becomes a fetus after 8 weeks.
- Second trimester: Rapid growth, skeleton development. Mother feels movement by 20 weeks.
- Third trimester: Significant brain growth; immune system development.
Extraembryonic membranes: Support for protection, nutrient and waste transport.

Reproductive Strategies

Fertilization Types:
- External fertilization: More offspring, lower chance of survival.
- Internal fertilization: Higher fertilization success, higher survival rate.
Reproduction methods (types of development):
- Oviparous: Lay eggs.
- Viviparous: Embryos develop inside the mother.
- Ovoviviparous: Embryos develop in eggs inside the mother.
Primary and Secondary sexual characteristics:
- Primary characteristics present at birth.
- Secondary characteristics develop during puberty for survival.

Hormonal Control (Reproductive Systems)

Male Reproductive Hormones:
- GnRH from hypothalamus, stimulating pituitary LH/FSH release.
- LH stimulates Leydig cells to produce testosterone.
- FSH regulates sperm production.
- Testosterone develops primary/secondary characteristics.
Female Reproductive Hormones:
- Estrogen: Enhances sperm production.
- Progesterone prepares the body for pregnancy.
- FSH stimulates ovarian follicle growth.
- LH matures oocyte and causes its release.

Assisted Reproductive Technologies (ART)

In Vitro Fertilization (IVF):
- Women take FSH to produce multiple eggs. Doctors collect them via a needle.
- Collected eggs are mixed with sperm in a dish; fertilized eggs develop.
- Selected embryos are implanted in the uterus.
- Used for blocked or damaged fallopian tubes, low sperm count.

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Description

Explore the fascinating processes of reproduction and development in organisms. This quiz covers the types of reproduction, fertilization stages, and the differentiation of cells in embryonic development. Test your knowledge on how these processes ensure species survival through genetic variation.