Sexual reproduction includes a reproductive pattern called _____.
Regeneration, the regrowth of lost body parts, normally follows _____.
Asexual reproduction results in offspring that are genetically identical to their parent. What type of cell process occurs to generate this type of offspring?
On a submarine expedition to the ocean bottom, you discover a population of fish that are only female. What type of reproduction does this fish most likely use?
Genetic mutations in asexually reproducing organisms lead to more evolutionary change than do genetic mutations in sexually reproducing ones because _____.
asexually reproducing organisms, but not sexually reproducing organisms, pass all mutations on to their offspring
Asexual reproduction results in greater reproductive success than does sexual reproduction when _____.
a species is in stable and favorable environments
Sexual reproduction _____.
can produce diverse phenotypes that may enhance survival of a population in a changing environment
Animals utilizing external fertilization are typically _____.
In close comparisons, external fertilization often yields more offspring than does internal fertilization. However, internal fertilization typically offers the advantage that _____.
the smaller number of offspring produced often receive a greater amount of parental investment
Which of the following correctly traces the path of sperm from their site of production to their exit from a man's body?
seminiferous tubule → epididymis → vas deferens → urethra
Which of the following structures in females is analogous in function to the vas deferens in males?
In humans, the follicular cells that remain behind in the ovary following ovulation become _____.
a steroid-hormone synthesizing structure called the corpus luteum
Mature human sperm and ova are similar in that they _____.
both have the same number of chromosomes
Among human males, both semen and urine normally travel along the _____.
Increasing the temperature of the human scrotum by 2°C (that is, near the normal body core temperature) and holding it there would most likely_____.
reduce the fertility of the man by impairing spermatogenesis
The primary difference between estrous and menstrual cycles is that _____.
the endometrium shed by the uterus during the estrous cycle is reabsorbed with no extensive fluid flow out of the body, whereas the shed endometrium of menstrual cycles is excreted from the body
A primary response by the Leydig cells in the testes to the presence of luteinizing hormone is an increase in the synthesis and secretion of _____.
The anatomical location for the typical union of a sperm and an egg (conception) is the _____.
Two contraceptive methods that are generally irreversible and which block the gametes from moving to a site where fertilization can occur are _____.
vasectomy and tubal ligation
An ectopic pregnancy occurs when a fertilized egg implants somewhere other than in the lining of the uterus. Usually it implants in the oviduct. Which of the following would be the most likely explanation for such a pregnancy being unsuccessful?
The lining of the oviduct is unable to support the developing fetus.
In male mammals, excretory and reproductive systems share
During human gestation, rudiments of all organs develop
in the first trimester.
Salamander and insect populations consisting only of genetically identical females lack males because _____.
sperm do not fuse with eggs during reproduction, but the eggs develop into embryos anyway
In humans, oogenesis in comparison to spermatogenesis is different in that _____.
oogenesis does not complete meiosis until after fertilization, but spermatogenesis is complete before the sperm leave the body
Human sperm cells first arise in the _____.
For which of the following is the number the same in spermatogenesis and oogenesis?
meiotic divisions required to produce each gamete
A fertilized egg usually implants itself and develops in the _____.
A rapid increase in the _____ level stimulates ovulation.
After ovulation, high levels of _____ inhibit _____ secretion.
estrogen and progesterone ... FSH and LH
Developing ovarian follicles primarily secrete _____.
If there is fertilization, secretion of _____ by the early embryo maintains the corpus luteum.
human chronic gonadotropin
If there is no fertilization, degeneration of the corpus luteum results in a drop in _____, which results in the sloughing off of the uterus's endometrium.
estrogen and progesterone
Ovulation usually occurs on or about day _____ of a 28-day ovarian cycle.
What is the usual site of the fertilization of an egg cell?
A reproductive hormone that is secreted directly from a structure in the brain is _____.
gonadotropin-releasing hormone (GnRH)