Life Processes in Plants and Animals - Grade 12

Flashcards based on lecture notes about life processes in plants and animals, focusing on the human endocrine system and reproduction.

What is the function of endocrine glands?

Produce chemicals called hormones that are released directly into the bloodstream and travel to a target organ to stimulate or inhibit it.

What hormones are produced by the pituitary gland and hypothalamus?

Growth hormone, TSH, FSH, and LH, ADH.

What hormone is produced by the thyroid gland?

Thyroxin.

What hormones are produced by the islets of Langerhans in the pancreas?

Insulin and glucagon.

What hormone is produced by the adrenal gland?

Adrenalin.

What hormones are produced by the gonads (sex organs)?

Testosterone (male); Oestrogen, progesterone, oxytocin and prolactin (female).

What condition arises from oversecretion of growth hormone?

Giantism (in children) and acromegaly (in adults).

What condition arises from undersecretion of growth hormone?

Dwarfism.

What is the function of Antidiuretic hormone (ADH)?

Regulates the reabsorption of fluid by the blood capillaries in the nephrons.

What are the effects of an oversupply of thyroxin?

Hyperthyroidism, causing nervousness and irritability.

What condition can result from iodine deficiency and insufficient thyroxin production?

Goitre, a swelling of the thyroid gland.

What conditions arise from an undersupply of thyroxin?

Cretinism (in children) and hypothyroidism (in adults).

What is the function of insulin?

Removes glucose from the blood and converts it into glycogen for storage.

What is the function of glucagon?

Converts glycogen back into glucose when cells require energy.

What condition results from insufficient insulin production?

Diabetes.

What are the effects of adrenalin production?

Increases heartbeat, breathing rate, muscle tone, blood glucose levels and blood pressure.

What is homeostasis?

Maintaining a stable internal environment.

What is the negative feedback mechanism in hormone production?

When the level of one hormone increases beyond the ideal, it causes the levels of a related hormone to drop.

Describe the initial step in the feedback loop between the pituitary and thyroid glands.

Pituitary produces TSH, which causes the thyroid to produce thyroxin.

How does the body respond to high levels of thyroxin in the blood?

If thyroxin levels are too high, the pituitary produces less TSH, decreasing thyroxin production.

Describe the feedback mechanism between glucagon and insulin.

Glucagon released into blood causes liver and muscle cells to convert glycogen into glucose; Insulin released into blood causes liver and muscle cells to convert glucose into glycogen

What is courtship?

Strategies used to select partners for reproduction.

Describe external fertilization and its characteristics.

Gametes are released directly into the water, without complex mating organs or specialized eggs required. High offspring mortality.

Describe internal fertilization and its characteristics.

Care is taken for gametes to meet safely inside the female's body. Fewer ova are produced, and the developing embryo is protected.

What are viviparous animals?

Animals that protect the developing embryos within their uteri.

What are ovoviviparous animals?

Animals that produce eggs but keep them inside the body of the female for additional protection and warmth.

What are oviparous animals?

Animals that lay eggs of some type.

What are the functions of the amnion in an amniotic egg?

Physical protection, protection from drying out, as well as space to move and grow.

What are examples of parental care?

Protection provided by a herd or nest-building and provision of food by birds to their young.

What are primary sexual characteristics?

Sex organs (gonads) and gametes produced.

What are secondary sexual characteristics?

Breast development or facial hair develop as a result of maturity of the gonads and the release of certain hormones.

What is the function of the bladder?

Produces urine that exits body via the urethra.

What is the function of the seminal vesicle?

Produces a fluid containing fructose which gives the sperm energy to swim.

What is the function of the epididymis?

Mass of tubing in which the sperm are stored.

What is the function of the testis?

Contains seminiferous tubules that produce sperm and the hormone testosterone.

What is the function of the sperm duct?

Connects the testis to the urethra.

What is the function of the scrotum?

Sac in which testes are found. Contains muscles which contract and pull the testes closer to the body in cool weather.

What is the function of the urethra?

Allows the release of semen (sperm + fluids).

What happens during spermatogenesis?

Cells in the germinal epithelium of the testes undergo mitosis and then each cell undergoes meiosis to form haploid spermatids, which develop tails as they mature.

What is the function of Sertoli cells?

Stimulates sperm production.

What is the function of Interstitial cells?

Stimulates testosterone production.

What changes occur during puberty in males due to increased testosterone production?

Increased muscle development, enlargement of the larynx causing the voice to deepen, hair growth.

What is the function of the ovary?

Produces eggs.

What is the function of the endometrium?

For implantation of developing zygote