CSET Practice Test Subtest II Science

Where Do Earthquakes Occur?

Stress that causes earthquakes is created by movement 
of almost rigid plates that fit together and make up the 
outer shell of the Earth. These plates "float" on a dense, 
more fluid layer just beneath them. The plates move at 
such a slow rate, about the same as a fingernail grows, 
that we do not notice it in our everyday lives. For 
instance, the Juan de Fuca plate off the coast of B.C. 
moves only about 4-5 cm/year relative to the North 
American plate. Over time, however, this small movement 
can build up enough stress to produce significant 
earthquakes. 

Earthquakes occur most frequently on, or near, the 
edges of plates where stress is most concentrated.

The Reproductive System

The reproduction system uses the process of producing 
a new generation to continue the existence of the species 
by the fusion of two cells from different individuals; this is 
achieved in humans by the fusion of one sperm and one 
ovum (egg). This fusion is called "fertilization" and is achieved 
by sexual intercourse between a male and female or by 
artificial insemination. The male body is designed to allow 
the manufacture, storage and transfer of male sex cells (or 
sperm). The female body is designed to manufacture, store 
and release eggs (ova). The creation of human life is a 
miracle to behold as two tiny cells - the sperm and the ovum 
- fuse to form a new cell which, after fertilization, resides in 
the female womb. Nine months later, a fully- formed, 
breathing, living human being in tiny replica is born. 

Animals' reproductive systems can be divided into the 
internal reproductive organs and the external genitalia. 
The gonads are the actual organs that produce the gametes. 
In the male, testes (singular = testis) produce sperm, and 
in the female, ovaries make eggs.

In most animals, individuals are either definite males or 
definite females. However, in some species, individual 
organisms are both male and female. Hermaphroditism is 
when one organism has both sexes. Earthworms and garden 
snails always have both male and female organs, and when, 
for example, two earthworms mate, they fertilize each other. 
A special variation on the theme is sequential hermaphroditism, 
in which an organism changes sex during its life. If an 
organism is female first and later changes to male, that 
organism is protogynous, and if the organism is male first 
and changes to female, it is said to be protandrous. In 
different species, sequential hermaphroditism can be 
influenced by the organism's age or size or by various 
environmental/climatic factors.

While most higher animals reproduce sexually, there are 
some species in which the females can, under certain 
conditions, produce offspring without mating. 
Parthenogenesis is the ability of an unfertilized egg to 
develop and hatch. This seems to be especially prevalent 
among insects. Some of the giant walkingsticks at the 
Zoo are females who, without mating, lay eggs that hatch 
into more females generation after generation. Other 
insects, like some aphids, have complicated life cycles 
that involve sexually-reproducing generations alternating 
with parthenogenically produced generations. In honeybees, 
fertilized eggs turn into females (workers and queens), 
while unfertilized eggs, which are only produced in the 
spring, turn into males.

In sexual reproduction, there must be some way of getting 
the sperm to the egg. Since sperm and eggs are designed 
to be in a watery environment, aquatic animals can make 
use of the water in which they live, but terrestrial animals 
must, in some way, provide the wet environment neeeded 
for the sperm to swim to the egg. There are, thus, two 
major mechanisms of fertilization. In external fertilization, 
used by many aquatic invertebrates, eggs and sperm are 
simultaneously shed into the water, and the sperm swim 
through the water to fertilze the egg. In internal fertilization, 
the eggs are fertilized within the reproductive tract of the 
female, and then are covered with eggshells and/or remain 
within the body of the female during their development.

In species with external fertilization, at an appropriate 
developmental stage, the eggs hatch, and the new young 
simply swim away. However, females of species with internal 
fertilization must, at some point, expel the growing young. 
There are three general ways of doing this:

Oviparous organisms, like chickens and turtles, lay eggs 
that continue to develop after being laid, and hatch later. 
Viviparous organisms, like humans and kangaroos, are 
live-bearing. The developing young spend proportionately 
more time within the female's reproductive tract, portions 
of which are specially-modified for this purpose. Young are 
later released to survive on their own. 
Ovoviviparous organisms, like guppies, garter snakes, and 
Madagascar hissing roaches, have eggs (with shells) that 
hatch as they are laid, making it look like "live birth." 

Female Reproductive System
The female reproductive system is illustrated to the right. 
"Eggs" are produced in the ovaries, but these are not true 
eggs and will never complete meiosis and become such 
unless/until first fertilized by a sperm. Within the ovary, a 
follicle consists of one precursor egg cell surrounded by 
special cells to nourish and protect it. A human female 
typically has about 400,000 follicles/potential eggs, all 
formed before birth. Only several hundred of these "eggs" 
will actually ever be released during her reproductive years. 
Normally, in humans, after the onset of puberty, due to the 
stimulation of follicle-stimulating hormone (FSH) one "egg" 
per cycle matures and is released from its ovary. Ovulation 
is the release of a mature "egg" due to the stimulation of 
leutenizing hormone (LH), which then stimulates the remaining 
follicle cells to turn into a corpus luteum which then secretes 
progesterone to prepare the uterus for possible implantation. 
If an egg is not fertilized and does not implant, the corpus 
luteum disintegrates and when it stops producing progesterone, 
the lining of the uterus breaks down and is shed.

Each "egg" is released into the abdominal cavity near the 
opening of one of the oviducts or Fallopian tubes. Cilia in 
the oviduct set up currents that draw the egg in. If sperm 
are present in the oviduct (if the couple has recently had 
intercourse), the egg will be fertilized near the far end of 
the Fallopian tube, will quickly finish meiosis, and the embryo 
will start to divide and grow as it travels to the uterus. The 
trip down the Fallopian tube takes about a week as the cilia 
in the tube propel the unfertilized "egg" or the embryo down 
to the uterus. At this point, if she had intercourse near the 
time of ovulation, the woman has no idea whether an 
unfertilized "egg" or a new baby is travelling down that tube. 
During this time, progesterone secreted by the corpus luteum 
has been stimulating the endometrium, the lining of the uterus, 
to thicken in preparation for possible implantation, and when a 
growing embryo finally reaches the uterus, it will implant in this 
nutritious environment and begin to secrete its own hormones 
to maintain the endometrium. If the "egg" was not fertilized, it 
dies and disintegrates, and as the corpus luteum also 
disintegrates, its progesterone production falls, and the 
unneeded, built-up endometrium is shed.

The uterus has thick, muscular walls and is very small. In a 
nulliparous woman, the uterus is only about 7 cm long by 4 to 
5 cm wide, but it can expand to hold a 4 kg baby. The lining of 
the uterus is called the endometrium, and has a rich capillary 
supply to bring food to any embryo that might implant there.

The bottom end of the uterus is called the cervix. The cervix 
secretes mucus, the consistency of which varies with the 
stages in her menstrual cycle. At ovulation, this cervical 
mucus is clear, runny, and conducive to sperm. Post-ovulation, 
the mucus gets thick and pasty to block sperm. Enough of this 
mucus is produced that it is possible for a woman to touch a 
finger to the opening of her vagina and obtain some of it. If 
she does this on a daily basis, she can use the information thus 
gained, along with daily temperature records, to tell where in 
her cycle she is. If a woman becomes pregnant, the cervical 
mucus forms a plug to seal off the uterus and protect the 
developing baby, and any medical procedure which involves 
removal of that plug carries the risk of introducing pathogens 
into the nearly-sterile uterine environment.

The vagina is a relatively-thin-walled chamber. It serves as 
a repository for sperm (it is where the penis is inserted), and 
also serves as the birth canal. Note that, unlike the male, the 
female has separate opening for the urinary tract and 
reproductive system. These openings are covered externally 
by two sets of skin folds. The thinner, inner folds are the labia 
minora and the thicker, outer ones are the labia majora. The 
labia minora contain erectile tissue like that in the penis, thus 
change shape when the woman is sexually aroused. The opening 
around the genital area is called the vestibule. There is a 
membrane called the hymen that partially covers the opening 
of the vagina. This is torn by the woman's first sexual intercourse 
(or sometimes other causes like injury or some kinds of vigorous 
physical activity). In women, the openings of the vagina and 
urethra are susceptible to bacterial infections if fecal bacteria 
are wiped towards them. Thus, while parents who are 
toilet-training a toddler usually wipe her from back to front, 
thus "imprinting" that sensation as feeling "right" to her, it is 
important, rather, that that little girls be taught to wipe 
themselves from the front to the back to help prevent vaginal 
and bladder infections. Older girls and women who were taught 
the wrong way need to make a conscious effort to change 
their habits.

At the anterior end of the labia, under the pubic bone, is the 
clitoris, the female equivalent of the penis. This small structure 
contains erectile tissue and many nerve endings in a sensitive 
glans within a prepuce which totally encloses the glans. This is 
the most sensitive point for female sexual stimulation. Some 
cultures do a procedure, similar to circumcision, as a puberty 
rite in teenage girls in which the prepuce is cut, exposing the 
extremely-sensitive clitoris. There are some interesting 
speculations on the cultural significance of this because the 
sensitivity of the exposed clitoris would probably make having 
sexual intercourse a much less pleasant experience for these 
women.

Source:
Special thanks to the University of Cincinnati Clermont 
College