Chapter 7: Reproduction and Embryonic Development

Comprehensive flashcards covering Chapter 7: Reproduction and Embryonic Development, including asexual/sexual modes, human anatomy, fertilization steps, and trimesters of pregnancy.

What is the definition of asexual reproduction?

The production of genetically identical offspring by a single parent, involving only mitotic cell division and no fusion of egg and sperm.

Which types of asexual reproduction are described with the examples Hydra and Sea anemone?

Budding (Hydra) and Fission (Sea anemone).

In what kind of environment is asexual reproduction most advantageous?

Stable environments where conditions remain constant, allowing identical offspring to thrive.

How does sexual reproduction define the creation of offspring?

It is the creation of offspring through fertilization, the union of haploid ($n$) gametes (sperm and egg) to form a diploid ($2n$) zygote.

What is the primary evolutionary advantage of sexual reproduction?

It creates genetic variation through meiosis and random fertilization, enhancing adaptation and survival in changing environments.

What is hermaphroditism and why is it beneficial for certain species?

A condition where an individual has both male and female reproductive systems; it is beneficial for animals with limited mobility or few potential mates as it ensures reproduction.

What is the difference between external and internal fertilization environments?

External fertilization typically occurs in aquatic environments, while internal fertilization is common in terrestrial animals to protect gametes from dehydration.

Where are follicles located and what is their function in the female reproductive system?

They are located in the ovaries; they consist of a developing egg cell and follicle cells that nourish and protect the egg.

What is the corpus luteum and what hormones does it secrete?

It is the tissue remaining from a follicle after ovulation; it secretes estrogen and progesterone to maintain the uterine lining.

Where does fertilization usually occur in the human female reproductive tract?

In the oviduct (Fallopian tube).

What is an ectopic pregnancy?

A condition where an embryo implants outside the uterus, most commonly in an oviduct (tubal pregnancy).

What is the function of the scrotum in the male reproductive system?

It is a pouch that holds the testes outside the body to keep them approximately 2^\regular{o}C cooler than body temperature, which is necessary for sperm production.

What is the role of the epididymis?

It is a coiled duct on the surface of the testis where sperm are stored and mature.

Which glands contribute secretions to form semen?

The seminal vesicles, prostate gland, and bulbourethral (Cowper's) glands.

How many functional gametes are produced from one primary spermatocyte versus one primary oocyte?

Spermatogenesis produces four functional sperm cells, while oogenesis produces one large ovum and three small polar bodies that degenerate.

At what developmental stage are a female's primary oocytes arrested until puberty?

Prophase I of meiosis.

What hormonal event specifically triggers ovulation around Day 14 of the cycle?

A sharp surge in LH (Luteinizing Hormone).

What is the function of hCG (human chorionic gonadotropin)?

It is released by the embryo if fertilization occurs to maintain the corpus luteum so that estrogen and progesterone levels remain high.

Which causative agents of STIs can be treated with antibiotics?

Bacterial agents such as Chlamydia trachomatis (Chlamydia), Neisseria gonorrhoeae (Gonorrhea), and Treponema pallidum (Syphilis).

Which contraceptive methods are considered the 'Most Reliable' with a less than $1\%$ risk of pregnancy?

Hormonal methods (pills, implants, etc.), IUDs (Intrauterine devices), and sterilization (vasectomy or tubal ligation).

What is the purpose of the acrosome in a sperm cell?

It is a cap containing enzymes that help the sperm penetrate the egg's jelly coat or zona pellucida.

What is the 'cortical reaction' during fertilization?

The release of cortical granules that lift the vitelline layer to form a fertilization envelope, creating a block to polyspermy (entry of more sperm).

What are the three primary germ layers formed during gastrulation?

Ectoderm (outer), Mesoderm (middle), and Endoderm (inner).

Which adult structures are derived from the ectoderm?

The epidermis of the skin, hair, nails, and the nervous system (brain, spinal cord, and sense organs).

What is the function of the notochord during organogenesis?

It acts as a supporting axis and a signaling center that induces the overlying ectoderm to form the neural tube.

What is apoptosis and provide an example during development?

Programmed cell death; for example, the death of cells between digits to form individual fingers and toes.

What are Homeotic (Hox) genes?

Master regulatory genes that control body plan organization and the placement of body parts by encoding transcription factors.

What does 'colinearity' refer to regarding Hox genes?

The phenomenon where the sequence of Hox genes on a chromosome corresponds to the order of body parts they regulate from head to tail.

What is the function of the extraembryonic membrane called the amnion?

It encloses the embryo in a fluid-filled sac that cushions the embryo, maintains temperature, and prevents dehydration.

What are the roles of the chorion and the yolk sac in human embryos?

The chorion forms part of the placenta for nutrient/gas exchange; the yolk sac provides the first source of nutrients and blood cells.

During which trimester does organogenesis and the appearance of a heartbeat occur?

The First Trimester (Weeks 1–12).

What is the function of surfactant produced in the lungs at Week 24?

It is a substance essential for breathing after birth; without it, the lungs of a premature infant might collapse.

Why is the first trimester the most sensitive period for developmental defects?

Because this is when organogenesis (the formation of major organ systems) occurs, making the embryo highly vulnerable to damage from drugs or toxins.