Grade 9-Science

Astronomical Unit (AU)

One astronomical unit equals the average distance between the Sun and the Earth, about 150 million kilometers.

Light Year (ly)

One light year equals the distance that a beam of light travels through space in one year, equivalent to 9 trillion kilometers.

Asteroid Belt

A huge band of billions of rocks circling the Sun, found between the inner rocky planets and the outer gas giants.

Dwarf Planets

Similar to planets in that they orbit the Sun and have a roughly spherical shape, but have an unusual orbit in a zone that contains many other objects.

Comets

A celestial object made of ice and dust, often called a 'dirty snowball', which travels in an elliptical orbit around the Sun.

Meteoroids

Small pieces of rock or metal that travel throughout the solar system with no fixed path.

Meteor

A meteoroid that after entering Earth's atmosphere, collides with gas molecules and burns up due to frictional heating.

Meteorite

A meteor that survives a trip through the atmosphere and hits the ground.

What causes day and night on Earth?

The daily rotation of Earth on its axis.

How does Earth rotate when viewed from the North Pole?

Counter-clockwise.

What are the two main seasons near the equator?

Wet and dry seasons.

How many seasons are generally experienced in the northern and southern hemispheres?

Four seasons.

What is the reason for the change in seasons?

The tilt of the Earth and its revolution around the Sun.

What is an orbit?

The curved, repeating path that one object takes around another, due to the force of gravity.

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What is a satellite?

Any object that orbits a planet; the Moon is a natural satellite of Earth.

Why does the Moon appear bright?

It reflects the Sun's light.

What occurs during a solar eclipse?

The Moon lies directly between the Earth and the Sun, blocking all or part of the Sun's light.

What occurs during a lunar eclipse?

The Earth blocks the Sun's light shining on the Moon, making the Moon briefly 'disappear'.

What is the approximate distance from the Earth to the Sun?

About 150 million kilometers.

What is a sunspot?

A region on the Sun's surface that is cooler than the surrounding area, appearing darker.

What is a solar prominence?

A large, low energy, curved bright stream of particles shaped by the Sun's magnetic field lines.

What is a solar flare?

A high energy explosion at the Sun's surface that flings hot plasma into space.

What is solar wind?

A steady stream of subatomic particles or plasma emitted from the Sun's surface.

What natural phenomenon is caused by the solar wind interacting with Earth's magnetic field?

Aurora Borealis (Northern Lights) and Aurora Australis (Southern Lights).

What is parallax

Parallax is the apparent shift in an object's position when viewed from two different points.

How are the planets lined up from the Sun?

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune

Why do we only see one side of the moon?

It is tidally locked with the Earth, meaning it rotates on its axis at the same rate (speed) it orbits our planet.

How is the sun, moon earth lined up during a lunar eclipse?

Sun, Earth, Moon (SEM)

How is the sun, moon earth lined up during a Solar eclipse?

Sun, Moon, Earth (SME)

What is a Solar Eclipse

When the Moon passes between the Sun and Earth, it casts a shadow on Earth that either fully or partially blocks the Sun's light in some areas.

What is a punnett square?

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Allele define

A possible version of a gene which codes for a specific trait.

How many alleles do you receive

You receive one allele from your biological mother and one from your biological father.

What is hetrozygous genes.

When both alleles are not the same (also hybrid)

What is homozygous genes

If both alleles are the same (pure).

What is a characteristic?

A feature of an organism, such as eye color or wing shape.

What is a Trait?

A variation of a characteristic, such as brown eyes vs blue eyes.

What is Heredity?

The transmission of characteristics from one generation to the next.

What are heritable characteristics?

Traits that can be passed down genetically from parent to offspring. Such as eye color or hair color.

What are Non-Heritable characteristics?

Traits that cannot be passed down from parent to offspring. Ex: Scars, piercings, tattoos.

What are discrete variations?

Traits that fall into distinct, separate categories. Such as blood type or the ability to roll one's tongue.

What are continuous variations?

Traits with a range of differences, with no distinct categories. Such as skin color, or Human height

What are chromosomes simple definition.

Chromosomes are bundles of tightly coiled DNA found in the nucleus of each cell.

What tiny structures does the nucleus contain?

Chromosomes.

Define Genes

A segment of DNA that contains instructions for a specific trait or function in the body. Which can be genetically passed down.

What did Gregor Mendel discover?

He created the Principles of Genetics.

What is the trait of a stronger gene called?

The stronger gene is called "The dominant gene".

What is the "hidden" gene called.

The hidden gene is called the recessive gene.

What are the possibilities of the gender of a baby rely on?

The gender depends entirely on chance.

What chromosomes do males have?

Males have XY chromosomes.

What chromsomes do females have?

Females have XX chromosomes.

Fertilization of a egg an X sperm produces…

A Female offspring

Fertilization of a egg an Y sperm produces…

A Male offspring

Eggs have only…

X sex chromosomes.

A Gamete has how many chromosomes.

A gamete has half the number of chromosomes found in a body.

What are sex-linked disorders

A genetic condition caused by a defect on a sex chromosome, either the X or Y chromosome.

Examples of sex-linked disorders

Color blindness, Hemophilia, Male pattern baldness.

Define phenotype

Refers to the physical characteristics of an organism.

Define Genotype

Refers to the genetic characteristics of an organism.

What is homozygous recessive

Someone with two of the same identical recessive alleles.

What is homozygous dominant

Someone who has two identical dominant alleles.

puberty

The period of growth and development of the final adult form and of sexual maturation. It is the time when hormones begin the changes that make our bodies produce mature gametes.

gonads

The reproductive organs that make gametes.

testes

The gonads in males that produce sperm and testosterone.

testosterone

The hormone responsible for developing secondary male sex characteristics.

secondary male sex characteristics

Characteristics such as broader shoulders, a deeper voice, and growth of body hair.

primary sex characteristics in males

The penis and testicles in males.

sperm

Mature gametes produced by males, which are capable of reproduction.

sperm production

Usually continues throughout a male's entire life.

scrotum

Sac that protects the testes and helps keep them cool.

epididymis

A structure on top of the testis that stores sperm.

vas deferens

Tubes where sperm travel from epididymis to the urethra.

urethra

Tube to the outside of the body that expels urine and semen.

prostate gland

Helps produce seminal fluid that combines with sperm to make semen.

testis

male reproductive gland responsible for producing sperm and male hormones, primarily testosterone

seminiferous tubules

Tiny tubes that produce sperm.

Penis

Organ that delivers sperm during reproduction

male reproductive system

The main function is to produce healthy active gametes and be able to transfer the gametes to the female.

Where are sperm cells made?

In the seminiferous tubules

Where do sperm cells mature?

In the epididymis

What is the path sperm cells take after maturing?

They travel through the vas deferens and urethra to leave the body.

advantage of scrotum

To keep the testes cool, which allows for better sperm production.

Vagina

A muscular tube that acts as the birth canal.

Uterus

A hollow, muscular organ where the fetus develops.

Follicle

Fluid filled sac in the ovary that stores egg cells held as second division of meiosis

Ovary

The gland that stores and releases eggs and produces estrogen and progesterone.

Cervix

The structure that connects the vagina to the uterus.

Fallopian Tube

The tube that guides an egg from the ovary to the uterus.

What are the gonads in females called?

Ovaries

What hormones do the ovaries produce?

Estrogen and progesterone

How many eggs does a female have at birth?

Approximately 1-2 million eggs

How many eggs will a female ovulate in her lifetime?

400-500 eggs

What happens during ovulation?

The release of the egg from the ovary

What is the menstrual cycle?

A precisely timed sequence of events in females that takes about 28 days

What prepares the endometrium for a potential pregnancy?

Increased levels of estrogen and progesterone

What happens if fertilization does not occur after ovulation?

The endometrium breaks down and is shed from the body in a process called menstruation

How long does menstruation usually last?

Four to seven days

What happens to an unfertilized egg after ovulation?

It will die in 24 to 48 hours, disintegrate, and leave the body

Define fertilization of an egg

The process where a male sperm cell fuses with a female egg (ovum) to form a zygote