Praxis Middle School Science-The Cell

Question 1

Name the parts of the eukaryotic cell.

Answer 1

1. nucleus
2. ribosomes
3. endoplasmic reticulum
4. golgi complex or golgi apparatus.
5. lysosomes
6. mitochondria
7. plastids
8. cell wall
9. vacuoles
10. cytoskeleton

Question 2

cytoskeleton

Answer 2

composed of protein attached to the plasma membrane and organelles.

Question 3

What are vacuoles?

Answer 3

Vacuoles hold stored food and pigments. Their size in plants allows them to fill with water in order to provide turgor pressure (without this the plant would wilt)

Question 4

What is the cell wall?

Answer 4

The cell wall is found in plant cells. It is composed of cellulose and fibers.

• It is thick enough to support and protect.
• It is porous enough to allow water and dissolved substances to enter.

Question 5

What are plastids?

Answer 5

Plastids are found in photosynthetic organisms.

-They have their own dna and can reproduce as needed for the increased capture of sunlight.

Question 6

Name three types of plastids.

Answer 6

1. chloroplasts: green, function in photosynthesis, capable of trapping sunlight
2. chromoplasts: give color to leaves
3. amyloplasts: store starch for food

Question 7

What are mitochondria?

Answer 7

Mitochondria supply energy to the cell

muscles are made of mitochondria because they use a great deal of energy

they have their own dna and are capable of reproducing themselves

Question 8

What are lysosomes?

Answer 8

Lysosomes contain digestive enzymes
-break down food, waste substances, viruses, damaged cell components and eventually the cell itself

mainly in animal cells

Question 9

What is the golgi apparatus?

Answer 9

stacked structure

sorts, modifies, and packages molecules that are made in other parts of the cell

these molecules are either sent out of the cell or to other organelles within the cell

Question 10

What is the nucleus?

Answer 10

The nucleus is the brain of the cell.

Question 11

Name the parts of the nucleus.

Answer 11

1. Chromosomes: dna, rna, and proteins tightly coiled.
2. -chromatin: loose structure of chromosomes, called chromatin when the cell is not dividing
3. nucleoli: where ribosomes are made, they’re dark spots in the nuclues
4. nuclear membrane: contains pores which let rna out of the nucleus

Question 12

Describe ribosomes.

Answer 12

the site of protein synthesis

Question 13

What is the endoplastic reticulum?

Answer 13

roadway

allows for transport of materials in and out of the cell

Question 14

What are the basic unit of living things?

Answer 14

The cell

Question 15

What are prokaryotic cells?

Answer 15

Prokaryotic cells include only bacteria and blue-green algae

have no defined nucleus

thick cell wall containing amino sugars

Question 16

What are eukaryotic cells?

Answer 16

Eukaryotic cells are found in protists, fungi, plants, and animals

have cytoplasm, a cytoskeleton, and more complex structures like organelles

Question 17

What is the purpose of cell division?

Answer 17

To provide growth and repair in body (somatic) cells and to replenish or create sex cells for reproduction

Question 18

What is mitosis?

Answer 18

the division of somatic (body) cells

two cells result from each division

chromosome number is identical

for cell growth and repair

Question 19

What are the two parts of mitosis?

Answer 19

1. mitotic phase: mitosis and cytokinesis divide the nucleus and cytoplasm, respectively.
   - 2. Interphase: the cell grows and copies the chromosomes in preparation for the mitotic phase.

Question 20

What are the three stages of interphase?

Answer 20

1. G1 growth period, when the cell is growing & metabolizing
2. S period (synthesis) is where new dna is made
3. G2 phase (growth) is where new protein and organelles are being made to prepare for cell division

Question 21

Cytokinesis

Answer 21

the process whereby the cytoplasm of a single cell is divided to produce two daughter cells

Question 22

cancer cells do not respond to

Answer 22

density dependent inhibition.

they divide excessively and invade other tissues.

Question 23

Density dependent inhibition

Answer 23

occurs when the cells crowd one another and consume all the nutrients, thereby halting cell division.

Question 24

What is cellular respiration?

Answer 24

the metabolic pathway in which food (glucose, etc) is broken down to produce energy in the form of ATP

Question 25

both plants and animals use respiration to

Answer 25

create energy for metabolism

Question 26

What is oxidation-reduction (redox reaction)

Answer 26

the process in respiration that releases energy through the sequential loss and gain of electrons

Question 27

What is the electron transport chain?

Answer 27

the final step in respiration that creates 34 molecules of ATP through oxidative phosphorylation

Question 28

Photosynthesis

Answer 28

an anabolic process that stores energy in the form of a three-carbon sugar.

Question 29

photosynthesis' two stages

Answer 29

1. light reactions: solar energy is converted to chemical energy 2. calvin cycle: energy from the light reactions is used to reduce carbon to sugar

Question 30

photosynthesis reverses

Answer 30

electron flow, using the sun's energy to split water into hydrogen and oxygen and reduce carbon dioxide to glucose.

Question 31

chloroplast

Answer 31

the site of photosynthesis

Question 32

autotroph

Answer 32

an organism that makes its own food from the energy of the sun or other elements

Question 33

What is meiosis?

Answer 33

division of sex cells four cells or polar bodies result from each division chromosomes number is half of the two parent cells recombinations provide genetic diversity

Question 34

gamete

Answer 34

A gamete is a sex cell or germ cell; sperm and eggs

Question 35

chromatin

Answer 35

loose chromosomes; the state of chromosomes when the cell is not dividing

Question 36

chromosome

Answer 36

A chromosome is a tightly coiled, visible chromatin this state is found when the cell is dividing

Question 37

What are homologues?

Answer 37

homologues are chromosomes that contain the same information, are of equal length, and contain the same genes

Question 38

What is a diploid?

Answer 38

2n number, diploid chromosomes are a pair of chromosomes in somatic cells

Question 39

haploid

Answer 39

1n number, half a pair (in sex cells)

Question 40

What are the stages of mitosis?

Answer 40

1. interphase: chromatin is loose, chromosomes are replicated, cell metabolism is occurring. 2. prophase: chromatin condenses to become visible chromosomes. nucleus disappears. nuclear membrane breaks apart. mitotic spindles form, cytoskeleton breaks down. spindles are pushed to the opposite ends of the cell. 3. metaphase: kinetchore fibers attach to the chromosomes, which cause them to line up in the middle of the cell. 4. anaphase: centromeres split in half and homologous chromosomes separate. chromosomes are pulled to the poles of the cell, with identical sets at either end. 5. telophase: two nuclei are formed, each with a full set of dna identical to the parent cell. nucleoli become visible, and nuclear membrane reassembles. a cell plate is visible in plant cells, and a cleavage furrow is formed in animal cells. the cell is pinched into two cells. cytokinesis or division of the cytoplasm and organelles occurs.

Question 41

meiosis stages

Answer 41

meiosis 1: chromosomes are replicated; cells remain diploid prophase 1: replicated chromosomes condense and pair with homologues to form a tetrad. cross over (the exchange of genetic material) anaphase 1: sister chromatids remain joined and move to the poles of the cell. telophase 1: two new cells are formed: chromosomes number is still diploid. meiosis 2: reduces the chromosome number in half prophase 2: chromosomes condense. metaphase 2: spindle fibers form again, sister chromatids line up in the center of the cell, centrometers divide, sister chromatids separate anaphase 2: separated chromosomes move to opposite ends telophase 2: four haploid cells form for each original sperm germ cell. one viable egg cell gets all the genetic info and 3 polar bodies form with no dna. the nuclear membrane reforms and cytokinesis occurs.