Cells & the Organization of the Body

Question 1

Know all the characteristics of life.

Answer 1

MRS GREEN
Mobility - move around to get food or stay away from predator
Reproduction - ability to produce offspring to keep species in existence
Sensitivity - respond and react to environment
Growth - development into an adult
Respiration - releasing energy from food (C6H12O6 + O2 → CO2 + H2O)
Exrection - Getting rid of waste (e.g., CO2, H2O, urea, ammonia, etc)
Evolution - gradual change of a species to adapt to its environment
Nutrition - need for food
Cells - building blocks of organisms (considered living things)

Question 2

Label the parts of a microscope.

Answer 2

Eyepiece: magnifies the primary image shown

Objective turret: has the objective lens

Objective lens: allows you to customize the magnification

Coarse focus: moves the stage to help bring the object into focus

Fine focus: also move the stage but enables you to get a more precise focus

Stage clips: keeps the slide in place

Slide: where the specimen is contained

Stage: the place where you put the slide

Illuminator: produces light that passes the thin and transparent specimen to help create an image

Illumination intensity knob: controls the light intensity

Iris diaphragm & condenser: has different size holes which makes the light go through a different sized opening

Question 3

Know the highest magnification of light and electron microscopes

Answer 3

Light microscopes: x 1500 magnification

Electron microscopes: x 500,000 magnification

Question 4

Know the size of a micrometres (µm) relative to other units, such as millimetres (mm) or centimetres (cm) and be able to convert cm and mm to µm. Be able to calculate the actual size of a specimen.

Answer 4

1 x 10^-6 m
Real size in µm = size of image in µm/magnification

Question 5

Understand cell theory and have a knowledge of its historical development, including the significant discoveries and the scientists who made them.

Answer 5

Discovery by Robert Hooke (1665)

Robert Brown discovers nucleus (1833)

Matthias Schleiden discovered cells in plants (1838)

Rudolf Virchow discovered diseases caused by injury to cell

Spontaneous Generation was disproved (belief that certain objects produce certain living thing e.g., rotten meat source of flies)

Question 6

What are the differences between eukaryotes and prokaryotes?

Answer 6

Prokaryotes are cells without nucleus and membrane-bound organelles

Eukaryotes are cells with nucleus and membrane-bound organelles

Question 7

Know the functions of the following organelles: cell membrane, cell wall, cytoplasm, vacuoles, chloroplasts, nucleus, mitochondria, ribosomes

Answer 7

Cell membrane: semi-permeable and allows specific molecules to enter and exit, keeps cells, known as keeping homeostasis

Cell wall: helps maintain structure and protection in cells

Cytoplasm: jelly-like substance that surrounds internal cell structures
Nucleus: Have chromatin (tangled, spread-out form of DNA); where genetic material in eukaryotes is put; controls cell’s activities; has nucleolus which is where ribosomes are produced

Vacuoles: stores materials, keeps plant cells firm, helps with waste disposal as they are specialised lysosomes

Chloroplasts: have green pigment called chlorophyll; obtain light energy to enable photosynthesis
Mitochondria: powerhouse of cells; utilise cellular respiration to make ATP (Adenosine Triphosphate) energy from glucose and oxygen

Ribosomes: make proteins with a chain of amino acids (synthesising); a lot of genetic material codes for proteins; can be free in cytoplasm or stuck to another organelle (e.g., endoplasmic reticulum)

Question 8

Compare the structures that are present in plant and animal cells seen with an electron microscope.

Answer 8

Animal cells:
Don’t have cell wall
Have cytoplasm
Have cell membrane
Have small vacuoles
Have mitochondria
Don’t have chloroplasts
Have nucleus
Have ribosomes

Plant cells:

Have cell wall
Have cytoplasm
Have cell membrane
Have a big, central vacuole
Have mitochondria
Have chloroplasts
Have nucleus
Have ribosomes

Question 9

What are the characteristics of animal cells?

Answer 9

• Multicellular
• Eukaryotic
• Heterotrophic
• Reproduce sexually
• Has nucleus, cell membrane, mitochondria, ribosomes, vacuoles, DNA

Question 10

What are the characteristics of plant cells?

Answer 10

• Multicellular
• Eukaryotic
• Autotrophic
• Reproduce sexually
• Usually receive energy - from photosynthesis
• Has nucleus, cell membrane, mitochondria, ribosomes, chloroplasts, vacuole, DNA, and cell wall

Question 11

What are the characteristics of fungus cells?

Answer 11

• Either unicellular or multicellular
• Eukaryotic
• Heterotrophic
• Reproduce sexually and asexually
• Food comes from dead, organic material or from living host (saprophytic or parasitic)
• Have thread-like parts called hyphae which make up a network called the mycellium
• Have nucleus, cell membrane, mitochondria, ribosomes, vacuole, DNA, and cell wall

Question 12

What are the characteristics of monera cells?

Answer 12

• Unicellular
• Too small to be seen with naked eye
• Prokaryotic
• Either heterotrophic or autophic
• Sometimes photosynthesize
• Reproduce asexually
• Have cell membrane, capsule, ribosomes, vacuole, DNA, cell wall, flagellum, allowing them to be motile

Question 13

What are the characteristics of Protista cells?

Answer 13

• Unicellular
• Eukaryotic
• Heterotrophic or autotrophic
• Sometimes photosynthesize
• Reproduce sexually or asexually
• Mostly live in aquatic habitats
• Motile
• Have nucleus, cell membrane, mitochondria, rarely capsules, sometimes chloroplasts, ribosomes, vacuoles, DNA, sometimes cell wall

Question 14

List two specialised animal and plant cells.

Answer 14

• Animals: anything you can possibly come up with
• Plants: root hair cells, palisade cells xylem cells, etc

Question 15

Describe the different types of stem cells and know their characteristics.

Answer 15

Totipotent: can become virtually any cells

Pluripotent: can become practically any cell, example is ESCs (embyronic stem cells) which are found in early embryos; have lots of potential in terms of application

Multipotent: can become a limited range of cells; adult stem cells are multipotent; used for tissue maintenance and repair and can only produce cells of the tissue they are found in

Question 16

Describe the main ethical issues surrounding the use of stem cells.

Answer 16

Killing embryos: the process of harvesting stem cells will kill the embryo

Stem cell cloning: the cloning for stem cells may make people question their individuality and uniqueness

Consent: some donors are not told that the egg cells they donate will be used for the purpose of creating stem cells for patients

Question 17

What are stem cells?

Answer 17

• Stem cells are cells found in multicellular organisms
• Have the unique property of being able to reproduce indefinitely and being able to specialise into a range of cells; are essential for self-renewal, regeneration, and repair

Question 18

How are stem cells harvested?

Answer 18

• Can be harvested from egg cells that develop into early embryos after a few day, and are then extracted. They then specialise into the desired cell to cure the disease, cancer, etc
• Stem cell cloning involves a patient’s cell and donated zygote with its nucleus taken out. They are then combined via nuclear transfer. This then develops into embryonic stem cells that are then specialised to cure said disease. The ESCs are immunologically compatible and can be transplanted into the patient

Question 19

What are the characteristics of viruses?

Answer 19

• Accelular
• Not considered living things
• Infect living hosts with disease for survival
• Have protein shells as well as DNA or RNA genomes

Question 20

Give examples of harmful and harmless bacteria.

Answer 20

Harmless: E. Coli, Lactobacillus acidophilus, etc

Harmful: Norovirus, salmonella, etc