Grade 9 Biology - Human Reproduction, Development, and Cell Processes Review

Comprehensive vocabulary flashcards covering the male and female reproductive systems, human development stages, the cell cycle, mitosis, meiosis, genetics, the integumentary system, and the skeletal system.

Epididymis

A structure located on top of each testis responsible for the maturation and storage of sperm.

Vas deferens

A duct leading away from the testis through which sperm travel.

Urethra

The tube that carries both semen and urine outside of the body through the penis.

Testes

Male reproductive glands that produce sperm and are located in the scrotum.

Seminal vesicles

Glands that contribute over half of the semen and secrete sugar, nutrients, proteins, and enzymes to provide energy for sperm.

Prostate and Bulbourethral glands

Glands that contribute an alkaline solution to neutralize acidic conditions sperm might encounter in the urethra and the female reproductive tract.

Semen

A nourishing fluid for the survival of sperm containing sperm, nourishment, and other fluids from the male reproductive glands.

Sperm Nucleus Chromosome Count

The human sperm nucleus contains $23$ chromosomes.

Sperm Midpiece

The part of the sperm cell where mitochondria are found.

GnRH (Gonadotropin-releasing hormone)

Produced by the hypothalamus, it acts on the anterior pituitary gland to increase the production of FSH and LH.

FSH (Follicle-stimulating hormone)

In males, it promotes the production of sperm in the testes; in females, it stimulates follicle maturation.

LH (Luteinizing hormone)

In males, it stimulates the production and secretion of testosterone; in females, a surge causes ovulation.

Testosterone

A steroid hormone made in the testes that helps sperm production and influences the development of male secondary sex characteristics at puberty.

Oviduct

The structure where fertilization normally occurs, also known as the Fallopian tube.

Corpus Luteum

The structure into which follicle cells change after ovulation; it produces high amounts of progesterone and some estrogen.

Endometrium

The lining of the uterus that sheds during the flow phase and where a blastocyst attaches during implantation.

Ovulation

The process where a follicle ruptures and releases an egg, typically occurring around day $14$ due to an LH surge.

Fertilization

The process of a sperm joining with an egg, restoring the diploid number of $46$ chromosomes.

Morula

A solid ball of $16$ cells formed by day $3$ of early development.

Blastocyst

A hollow ball of cells formed by day $5$ that attaches to the endometrium during uterine implantation.

Inner cell mass

A group of cells inside the blastocyst that eventually becomes the embryo.

Placenta

An organ that contains tissue from both mother and fetus, where nutrients, oxygen, and wastes are exchanged.

Umbilical cord

The structure that joins the fetus to the placenta, containing the umbilical vein and umbilical arteries.

Amniotic fluid

Fluid in the amnion that protects, cushions, and insulates the developing fetus.

Fetus

The name given to the developing embryo at the end of eight weeks in the first trimester.

Amniocentesis

A prenatal test usually performed in the second trimester where fluid is removed from the amniotic sac for enzyme tests or DNA analysis.

Surface Area to Volume Ratio

A ratio that decreases as a cell grows larger, making the transport of nutrients and waste less efficient.

Interphase

The longest stage of the cell cycle where the cell grows, carries out normal processes, and replicates DNA.

Synthesis (S) phase

The substage of interphase during which the cell duplicates its DNA.

Mitosis

The stage of the cell cycle where the cell nucleus and nuclear material divide into four substages.

Cytokinesis

The process by which a cell's cytoplasm divides, resulting in two cells with identical nuclei.

Cleavage furrow

The constriction of microfilaments that pinches the cytoplasm in half during cytokinesis in animal cells.

Cell plate

The structure that forms between two daughter nuclei during cytokinesis in plant cells.

Cyclins

Proteins that bind to cyclin-dependent kinases (CDKs) to drive and control different stages of the cell cycle.

Cancer

The uncontrolled growth and division of cells resulting from a failure in the regulation of the cell cycle.

Carcinogens

Substances and agents that are known to cause cancer.

Crossing over

A process during prophase I of meiosis where chromosomal segments are exchanged between a pair of homologous chromosomes.

Nondisjunction

Cell division during which sister chromatids fail to separate properly, potentially resulting in extra or missing chromosomes.

Trisomy 21

A genetic disorder, also known as Down syndrome, where a person has three copies of chromosome number $21$.

Karyotype

A micrograph in which the pairs of homologous chromosomes are arranged in decreasing size.

Stem cells

Unspecialized cells that can be directed to become specialized cells such as nerve, muscle, or blood cells.

Keratin

A protein in the outer layers of the epidermis that waterproofs and protects skin tissue.

Melanin

A pigment in the inner layers of the epidermis that absorbs light energy and protects cells from ultraviolet rays.

Dermis

The second layer of skin containing connective tissue, blood vessels, muscle tissue, oil glands, and nerve tissue.

Sebaceous gland

A gland in the dermis that produces oil.

First-degree burn

A burn where cells in the epidermis are injured, causing redness, swelling, and mild pain.

Second-degree burn

A burn where cells in both the epidermis and dermis are injured or die, characterized by blisters and pain.

Third-degree burn

A severe burn where skin function is lost due to the death of epidermis and dermis cells and damage to nerve and muscle cells.

Compact bone

The dense and strong outer layer of all bones, containing tube-like structures called osteons or Haversian systems.

Spongy bone

Less dense bone with many cavities containing bone marrow, found at the ends of long bones and centers of flat bones.

Red bone marrow

The site where red and white blood cells and platelets are produced.

Yellow bone marrow

Found in many bones and consists primarily of fat; can be converted back to red marrow in cases of extreme blood loss.

Ball-and-socket joint

Joints found in the hips and shoulders that allow swinging movement of arms and legs.

Hinge joint

Joints found in elbows and knees that allow back-and-forth movement like a door hinge.

Gliding joint

Joints found in wrists, ankles, and vertebrae that allow side-to-side and back-and-forth movement.

Sutures

Unmovable joints found in the skull.