1.1 Introduction to Cells Vocabulary

Question 1

Cell Theory

Answer 1

1. All living things are composed of cells
2. The cell is the smallest fundamental unit of life
3. Cells only arise from pre-existing cells

Question 2

Exception to cell theory - striated muscle fibers

Answer 2

• Muscle cells fuse to form fibers that are very long/large
• Therefore have multiple nuclei despite being surrounded by singular, continuous membrane
• Challenges idea that cells always function as autonomous units

Question 3

Exception to cell theory - aseptate fungal hyphae

Answer 3

• Fungi may have filamentous structure called hyphae, which are separated by into cells by internal walls called septa
• Some fungi do not have septa and therefore have a continuous cytoplasm along the length of the hyphae
• Challenges idea that living structures are composed of discrete cells

Question 4

Exception to cell theory - giant algae

Answer 4

• Certain species of unicellular algae may grow to very large size (e.g. Acetabularia may exceed 7 cm in length)
• Challenges idea that larger organisms are always composed of many microscopic cells

Question 5

Exception to cell theory - question

Answer 5

If all cells arise from pre-existing cells, where did the first cell come from?

Question 6

7 basic functions of life

Answer 6

M - Metabolism
R - Reproduction
S - Sensitivity
H - Homeostasis
E - Excretion
N - Nutrition
G - Growth

Mnemonic: MR SHENG

Question 7

Basic function of life: Metabolism

Answer 7

Living things undertake essential chemical reactions

Question 8

Basic function of life: Reproduction

Answer 8

Living things produce offspring, either sexually or asexually

Question 9

Basic function of life: Sensitivity

Answer 9

Living things are responsive to internal and external stimuli

Question 10

Basic function of life: Homeostasis

Answer 10

Living things maintain a stable internal environment

Question 11

Basic function of life: Excretion

Answer 11

Living things exhibit the removal of waste products

Question 12

Basic function of life: Nutrition

Answer 12

Living things exchange materials and gases with the environment

Question 13

Basic function of life: Growth

Answer 13

Living things can move and change shape or size

Question 14

Investigating functions of life in Paramecium

Answer 14

• Metabolism: Most metabolic pathways happen in the cytoplasm
• Reproduction: The nucleus can divide to support cell division by mitosis, often asexual
• Sensitivity: Wave action of the cilia moves Paramecium in response to changes in the environment e.g. towards food
• Homeostasis: Contractile vacuoles fill up with water and expel through plasma membrane to manage water content
• Excretion: The plasma membrane controls the entry and exit of substances including the expulsion of metabolic waste
• Nutrition: Food vacuoles contain organisms Paramecium has consumed
• Growth: After consuming and assimilating biomass from food, Paramecium will grow larger until it divides

Question 15

Investigating the functions of life in Chlorella

Answer 15

Metabolism: Most metabolic pathways happen in the cytoplasm (same as Paramecium)

Reproduction: The nucleus can divide to support cell division by mitosis (same as Paramecium) and cells are undergoing cytokinesis

Sensitivity: The wave action of cilia moves Chlorella in response to changes in the environment (same as Paramecium) e.g. towards light

Homeostasis: Contractile vacuoles fill up with water and expel through plasma membrane to manage water content

Excretion: The plasma membrane controls the entry and exit of substances including diffusion out of oxygen waste

Nutrition: Chloroplasts undergo photosynthesis to produce food for algae

Growth: After consuming and assimilating biomass from food, the algae will grow larger until it divides

Question 16

Paramecium

Answer 16

• Unicellular
• Ciliated protist
• Heterotroph
• Freshwater environments

Question 17

Chlorella

Answer 17

• Unicellular
• Green algae
• Autotroph
• Dietary supplement

Question 18

Cellular energy exchange

Answer 18

Process of exchanging materials with the environment to produce chemical energy for cellular metabolism

Question 19

Rate of metabolism

Answer 19

Function of a cell’s mass/volume (larger cells need more energy to sustain essential functions)

Question 20

Rate of material exchange

Answer 20

Function of a cell’s surface area (large membrane surface = more material exchange)

Question 21

Surface area to volume ratio (SA:Vol)

Answer 21

The ratio between a cell’s surface area and its volume, which impacts the efficiency of material exchange and metabolic processes

Question 22

Decreased SA:Vol ratio

Answer 22

• Occurs when a cell grows and volume increases faster than surface area
• If rate of metabolism (volume) exceeds rate of material exchange (surface area) the cell will eventually die

Question 23

Suitable SA:Vol ratio

Answer 23

Growing cells tend to divide and remain small in order to maintain a ratio suitable for survival

Question 24

Increasing SA:Vol ratio

Answer 24

• Cells and tissues specialized for gas or material exchanges will increase SA to optimize rate of material exchange
• Intestinal tissue of the digestive tract may form a ruffled structure (villi) to increase SA of inner lining
• Alveoli in lungs have membranous structures called microvilli which increase total membrane SA

Question 25

Magnification equation

Answer 25

Magnification = Image size / Actual size

M = I / A

Question 26

Actual size equation

Answer 26

Actual size = Image size / Magnification

A = I / M

Question 27

Magnification unit conversion

Answer 27

• Centimeters to Millimeters (cm to mm):
  cm × 10 = mm
• Millimeters to Micrometers (mm to µm):
  mm × 1000 = µm
• Micrometers to Nanometers (µm to nm):
  µm × 1000 = nm