Cells

Question 1

The cell theory

Answer 1

• living things are composed of cells
• they are formed by pre-existing cells
• they derive their structure, function and organization from their cells

Question 2

Surface area and cells

Answer 2

• the shape of cells are small in order to allow there to be a greater surface area to volume ratio
• this is to have more area for nutrients to diffuse into the cell

Question 3

Cell membrane

Answer 3

• forms a protective barrier around the cell

* selectively permeable to regulate what enters and leaves the cell

Question 4

Cytoplasm

Answer 4

• contains nutrients required by the cell to carry its life processes

Question 5

Nucleus

Answer 5

• control center organelle
• controls activities such as growth and reproduction
• contains DNA

Question 6

Nucleolus

Answer 6

• the inner section of the nucleus

* produce ribosomes

Question 7

Vacuoles and vesicles

Answer 7

• membrane-bound organelles that store nutrients and waste

* plant cells have one large central vacuole

Question 8

Mitochondria

Answer 8

• releases the energy of food for the cell in carbon dioxide and water
• cellular respiration

Question 9

Lysosomes

Answer 9

• where digestion takes place
• filled with enzymes
• break down invading bacteria and damaged cells

Question 10

Golgi apparatus

Answer 10

• receives proteins from endoplasmic reticulum

* modifies, sorts, and packages protein into vesicles for delivery

Question 11

Rough endoplasmic reticulum

Answer 11

• carries material throughout the cell
• makes proteins
• contains ribosomes

Question 12

Ribosomes

Answer 12

• may be attached to the rough endoplasmic reticulum

* where proteins are produced

Question 13

Smooth endoplasmic reticulum

Answer 13

• carries material throughout the cell

* produces fats and oils

Question 14

Cytoskeleton

Answer 14

• internal network of fibers

* helps maintain the shape

Question 15

Cell wall

Answer 15

• found only in plant cells

* rigid frame that provides strength, protection, and support

Question 16

Chloroplasts

Answer 16

• found only in plant cells
• contain chlorophyll
• photosynthesis = make food from carbon dioxide and water
• used for the growth of the plant

Question 17

Centrosomes

Answer 17

• found only in animal cells
• guide the movements of chromosomes in cell division
• contain centrioles

Question 18

Interphase

Answer 18

• cells are doing their normal activities (acquiring nutrients, eliminating waste, growth)
• their DNA is in the form of chromatin
• the DNA replicates, forming two copies

Question 19

Prophase

Answer 19

• the nucleus dissolves
• chromatin thickens into chromosomes
• each chromosome has two identical copies called chromatids and are attached by centromeres
• nucleoli disappear
• centrioles (only in animal cells), move towards the poles of the cell
• spindle fibers form that radiate outward from the centrioles

Question 20

Metaphase

Answer 20

• the chromosomes line up along the equator of the cell

* they appear lined up in the middle of the cell

Question 21

Anaphase

Answer 21

• the centromeres break, allowing the chromatids to separate into new chromosomes called daughter chromosomes
• the daughter chromosomes follow the spindle fibers toward the poles of the cell

Question 22

Telophase

Answer 22

• nuclear membranes start forming around the daughter chromosomes
• nucleoli reappear
• the spindle fibers dissolve

Question 23

Cytokinesis

Answer 23

• redistribution of existing cytoplasm and organelles to the new daughter cells
• animal cell membranes pinch in around the centre, forming a cleavage furrow
• plant cell walls cannot pinch like this, so a cells plate forms between the daughter cells, and later hardens into a new cell wall

Question 24

Generalist cells

Answer 24

• the single cell of unicellular organisms has to be able to carry out all the functions of life = locomotion, gas exchange, absorption of food

Question 25

Multicellular organisms

Answer 25

* as organisms grow, their cells must divide to provide a better surface area to volume ratio * therefore larger organisms will contain more than one cell

Question 26

Cell differentiation

Answer 26

* multicellularity allows the specialization of cells for particular tasks * specialized cells do specific jobs better, at the expense of other functions * this makes different types of specialized cells dependent on each other

Question 27

Types of stem cells

Answer 27

* totipotent = can produce every differentiated cell in an organism * pluripotent = can produce any fetal or adult cell type, except the placenta * multipotent = can produce a few different types of cells