Praxis Grades 4-8 subject concentration:science Flashcards
A magnet could be most easily used to separate a mixture of sulfur and A. Salt B. Iron C. sugar D. Silicon
B. Iron because iron is a magnetic material and sulfur is not, they can be separated. The other materials are not magnetic.
When the sun, the moon, and the Earth are alligned with the moon in between the Sun and earth at point x facing both the moon and sun what would you see looking up from Earth?
A. The moon passing through Earth’s shadow.
B. A solar eclipse
C. The moon in its full phase.
D. The sun setting below the horizon.
Solar eclipse-B is correct. The moon would cover the Sun and there would be a solar eclipse. A lunar eclipse occurs when the earth is directly between the sun and the moon and the moon passes through the Earth’s shadow.
Which of the following is true about volcanic activity on Earth?
A. It usually occurs at tectonic plate boundaries.
B. It is rarely associated with earthquake activity.
C. It produces only metamorphic rocks.
D. It only produces lava with a temperature below the flash point of wood.
The correct answer is A. Most volcanoes are located at tectonic plate boundaries. There are exception to this: for example volcanoes in Hawaii form over a hot spot. Volcanic eruptions are typically associated with seismic activity. Lava cools to form igneous rock.
True statements about sickle-cell anemia include which of the following.
I. It is characterized by abnormal hemoglobin in red blood cells.
II. It is an inherited disease.
III. It can be life threatening disease.
IV. It can be permanently cured with prompt treatment.
A. I and II only
B. II and III only
C. I, II, and III only
D. I, II, III, and IV
C-Sickle cell anemia is a genetically based disorder of the red blood cells, or erythrocytes. It is characterized by abnormal hemoglobins, which is the molecule in red blood cells that carries the oxygen in the red blood stream. It is inherited and can be a life threatening disease. There is no permanent cure and can be passed on to the next generation. It can however be treated.
Refraction, the bending of light rays is the fundamental property underlying the operation of all of the following EXCEPT A. a magnifying glass B. a pair of binoculars C. an incandescent bulb D. a motion-picture projector
C. An incandescent bulb-Refraction is a fundamental property of all others because they all involve the use of lenses to focus light. The light bulb is the phenomenon of incandescence-the emission of visible light by a hot body.
Light travels at 3 X 10 to the 8th meters per second in a vacuum. Approximately how long after a huge flare erupts on the Sun’s surface is the flare seen on Earth, which is 1.5 X 10 to the 11th meters away?
C-The time t it takes for light to travel a distance d is given by the equation t=d/c where c is the speed of light, Thus t=d/c= 1.5 X 10 to the 11th/3 X 10 to the 8th m/s=500 sec X 1 min/60s=8min
DNA-figuring out father of child
Since the DNA of the child is a combination of parental DNA each band shown for the child must correspond to the bands shown for one or both parents. Based on the bands shown FY could only be the father because there are several bands common between the DNA patterns of the child and father.
Ancient astronomers were able to distinguish between the stars and the planets because the planets appeared to
A. Move with respect to the stars.
B. be brighter than the stars.
C. have surface features.
D. be different in color and smaller than most stars.
A. Move with respect to the stars-relative to the stars . The word planet comes from the GReek for wandering star.
Which of the following best accounts for the observation that, after combing, dry hair is attracted toward the comb.
A. The comb and hare are similarly charged.
B. The comb and hair are oppositely charged.
C. Protons move from the comb to the hair.
D. Protons move from the hair to the comb.
B-opposite charges.
As a result of combing, electrons are transferred from the dry hair to the comb, leaving the hair positively charged and the comb negatively charged. Because opposites attract, the dry hair is attracted to the comb.
6/3Li + 1/0n -? + 4/2He Bombardment of 6/3 Li with neutrons, as shown above, will yield which of the following atoms? A. 11/5B B. 9/4Be C. 4/2He D. 3/1H
D. Let A/Z X denote the unknown element X with atomic number Z and mass number A. The atomic number on both sides of the reaction must balance, an so must the mass numbers. Balancing the atomic numbers give the equation 3 + 0=Z + 2, or Z=1. An atomic number of Z=1 corresponds to the element hydrogen, H. Balancing the mass numbers gives the equation 6 + 1=A + 4, or A=3. Thus the unknown is 3/1H
The volume of 1 g of liquid water at a temperature of 4 degrees C and a pressure of 1 atm is A. 0.1 cm cubed B. 1 cm cubed C. 3 cm cubed D. 10 cm cubed
The correct answer is B. The volume of 1 g of H2O at 4 degrees C and 1 atm is 1 mL or 1 cm cubed.
Of the following planets, which takes the LEAST number of Earth days to revolve around the Sun? A. Neptune B. Jupiter C. Venus D. Mars
The correct answer is C-Venus. The closer a planet is to the Sun, the less time it takes for the planet to make one complete orbit around the Sun.
Which of the following is an example of asexual reproduction?
A. The growth of an oak tree from an acorn buried by a squirrel.
B. The earthworm’s use of sperm stored in its body to fertilize eggs that are produced by the earthworm.
C. The formation of a new Hydra by budding from the parent Hydra.
D. The transfer of pollen between flowering plants by foraging worker bees.
C-The formation of a new Hydra by budding from the parent Hydra. Asexual reproduction enables organisms to produce offspring that are genetically identical to themselves. There is only one parent, so the offspring are essentially clones of the parent. Hydra can reproduce sexually or asexually. In budding a clump of mitotically dividing cells of the parent forms into a new hydra.
One of woman’s X chromosomes carries the recessive allele for a sex-linked trait. Her other X chromosome carries the dominant allele for the trait. Which of the following is true about the woman and her sons?
A. She will express the trait, and her sons may or may not express the trait.
B. She will not express the trait, but her sons will express the trait.
C. She will not express the trait, and her sons may or may not express the trait.
D. Neither she nor her sons will express the trait.
C-The woman is heterozygous for the trait, that is she has one dominant allele and one recessive allele, so she will not express the trait. As males have only one X chromosome they will have only one allele for the trait and will express that allele. Since the woman can pass either of her X chromosomes to a son, her sons have a 50 percent chance of receiving the dominant allele and not expressing the trait and a 50 percent chance of receiving the recessive allele and expressing the trait.
The pitch perceived by a musician listening to a sound is analogous to which of the following wave properties? A. Frequency B. Speed C. Amplitude D. Intensity
A-frequency. The perceived pitch of a sound is the ear’s response to the frequency of the sound wave. In a practical sense, pitch and frequency are the same.
