biology sem 2 unit 2

Question 1

2 reasons why cells divide

Answer 1

DNA overload and inefficiency of the cell membrane

Question 2

Explain what DNA overload means

Answer 2

the larger the cell becomes the more demands the cell places on its dna

Question 3

Explain what happens to the surface and volume ratio as a cell enlarges

Answer 3

Surface area increases while the volume decreases

Question 4

In a living cell, what part of the cell represents surface area

Answer 4

the rate at which nutrients, oxygen, and water enter the cell and C02 and waste products leave the cell. The rate at which this exchange happens depends on the surface area. Which is also the total area of its cell membrane

Question 5

which part of the cell represents volume

Answer 5

rate at which food and O2 are used up and wastes are produced depends on the cell’s volume

Question 6

What are some adaptations that cells have developed that allow for a greater surface area volume ratio?

Answer 6

Cell division

Question 7

what are the 2 main stages of cell division

Answer 7

Interphase and m phase

Question 8

What is the cell cycle

Answer 8

A series of events that cells go through as they grow and divide

Question 9

What are the 4 stages of the cell cycle

Answer 9

G1, S, G2, M

Question 9

Explain each stage of the cell cycle

Answer 9

G1- growth and development, G0- where cells go that don’t divide, S- dna replication, G2- when the cell gets ready for mitosis, M- where mitosis and cytokinesis occur (division of the cell)

Question 10

What is the G0 stage? Give 3 examples of cells that, once matured in the G1 phase, enter the G0 stage indefinitely

Answer 10

G0 phase is where cells go that won’t divide latter on. Sperm cells, egg cells, and red blood cells

Question 11

Cells spend most of their lifetime in what stage? What 3 phases of the cell cycle does this include

Answer 11

interphase-> G1, S, and G2

Question 12

What are the four stages of mitosis, in order

Answer 12

Prophase, metaphase, anaphase, telophase

Question 13

what happens in the prophase stage

Answer 13

chromatin condenses into chromosomes. Centrioles separate and spindles begin to form. Nuclear envelope disolves. 1st visible sign of cell division and longest phase of mitosis.

Question 14

what happens in the metaphase stage

Answer 14

chromosmoes line up down the middle of the cell. Each chromosome is connected to spindle fibers. Shortest phase.

Question 15

what happens in the anaphase stage

Answer 15

the sister chromatids separate into individual chromosomes and are moved appart.

Question 16

what happens in the telophase stage

Answer 16

the chromosomes gather at opposite ends of the cell and 2 nuclear envelopes will form

Question 17

difference between chromatin and chromosome in structure

Answer 17

chromatin-dna is wrapped around proteins called histones which are bundled further into nucleosomes. Chromosomes- condensed and supercoiled chromatin fibers

Question 18

difference between chromosome and chromatin appearance

Answer 18

chromatin- long, thin and loosely coiled. Chromosomes- tightly wound, supercoiled

Question 19

difference between chromosome and chromatin organization

Answer 19

chromatin- not in an organized fashion but is spread throughout the nucleus, which makes replication and transcription easier. Chromosomes- in an organized fashion, necessary and helpful for cell division

Question 20

difference between chromosome and chromatin presence in the cell

Answer 20

chromatin- found throughout interphase. Chromosomes- seen only during cell division

Question 21

difference between chromosome and chromatin visualization on a microscope

Answer 21

chromatin- appears as beads on a string when stained and under electron microscope. Chromosomes- can be seen with a powerful light microscope

Question 22

explain how six feet of DNA is packed into the nucleus of every cell of our body

Answer 22

the dna wraps itself around histones then wraps itself again and clumps into 8 histones called nucleosomes. The dna becomes officially loosely coiled or chromatin. Then when it’s ready to divide it becomes super coiled into a chromosome

Question 23

How many chromosomes are found in human body cells and human sex cells (egg and sperm)

Answer 23

46 chromosomes in the human body cells and 23 in egg and sperm

Question 24

What is the name of the proteins that regulate the cell cycle

Answer 24

cyclin

Question 25

Define cancer

Answer 25

a result of uncontrolled cell growth

Question 26

What are tumors and what are the 2 types of tumors

Answer 26

a mass of cancer cells, benign- doesn’t spread to surrounding healthy tissue or other parts of the body. Malignant- they invade and destroy surrounding healthy tissue

Question 27

What causes cancer

Answer 27

defects in genes that regulate cell growth and division

Question 28

What are the 3 most common ways to treat cancer

Answer 28

surgery, chemotherapy, radiation

Question 29

What is apoptosis?

Answer 29

When a cell is programmed to die