PAQ SET 1: Living Organisms, Structures, Functions ,

Centrioles are normally present in the

• cytoplasm of onion cells

• cytoplasm of cheek cells

• nuclei of liver cells

• nuclei of bean cells

Answer explanation

Centrioles are only in ANIMAL cells

so that means answers with "bean cells" and "onion cells" are out.

Also, only DNA is found in the nucleus :)

The ribosomes of plant cells are sites for the synthesis of

Hint: Synthesis means making or production

"synthesize means to make"

• ATP

• Sugar

• Nucleic Acids

• Enzymes

Answer explanation

SEE THROUGH THE Q!

Ribosomes are protein factories;

ribosomes synthesize (make) proteins.

Without knowing what the term "enzymes" means, the other answers are NOT proteins so they can't be correct :)

Enzymes are a special TYPE of protein that speeds up chemical reactions in organisms.

Centrioles are cell structures involved primarily in

• cell division

• storage of fats

• enzyme production

• cellular respiration

Most cellular respiration in plants takes place in organelles known as

• ribosomes

• chloroplasts

• mitochondria

• cell wall

Answer explanation

Mitochondria are known as the "powerhouse" of cells because they:

*** turn food/chemical energy into USABLE energy called ATP.***

***Cellular respiration is the process of converting (changing) chemical/food energy into usable energy ATP.

***Mitochondria perform cellular respiration and make usable energy for all cells.

***Mitochondria are found in BOTH PLANTS and ANIMAL cells.

Which statement best describes the plasma membrane of a living plant cell?

• It selectively regulates the passage of substances into and out of the cell.
  

• It is composed of proteins and carbohydrates only.
  

• It has the same permeability to all substances found inside or outside the cell.

• It is a double protein layer with floating lipid molecules.

Answer explanation

Selectively permeable = semi-permeable

semi means partly or partially

Cell membranes only letting certain molecules in or out and controlling the FLOW of materials in and out is essential to cell functioning.

***Cell membranes are made of:

1) ***PHOSPHOLIPID BILAYER

• -like a sandwich, it has two layers made MSOTLY of lipids (fat molecules)

  • -Cell membranes are MOSTLY FAT

2) Have some proteins that go across them - transmembrane/helper proteins-, which help some molecules pass through the membrane into or out of the cell.

3) Also can have glycoproteins and carbohydrates that serve as receptors and recognize certain target molecules.

More on the importance of the cell membrane REGULATING flow of material and being selectively permeable:

Cell membranes let some things in and out easily like non-polar small molecules (oxygen gas and carbon dioxide).

Cell membranes also allow glucose (sugar) to cross the membrane - but these use a special helper protein that goes across the membrane like a channel.

Cell membranes DO NOT let big, bulky material into or out of the cell

-Starch is a BIG carbohydrate (made from lots of baby sugar molecules).

-Starch CANNOT pass through the membrane. It must be digested and broken down to simple sugar first.

-BIG HUGE fat molecules cannot go across the membrane - they too need to be broken down.

Which structures are found in every living cell?

• a cell wall and nucleus

• a plasma membrane and cytoplasm

• chloroplasts and mitochondria

• centrioles and chromosomes

Answer explanation

Watch out for half-true or partly-true answer choices!

Wrong answers explained:

Cell walls are ONLY in plant cells

Chloroplasts are ONLY in plant cells

Centrioles are ONLY in animal cells

In the diagram of a cell below, the structure labeled X enables the cell to

• release energy

• store water and waste products

• manufacture proteins

• control nuclear division

Answer explanation

Plant cells have LARGE CENTRAL VACUOLES important in storing water and in storing waste/food.

Animal cells also have vacuoles but they are smaller and mainly store waste and materials.

 Most of the reactions of aerobic cellular respiration occur within the organelle known as the

Aerobic just means with oxygen

Anaerobic means without oxygen

"-Ana " in front of a word means without

• lysosome

• nucleus

• mitochondria

• vacuole

. Which organelles' activity contributes most directly to muscle contraction in an earthworm?

Hint: Muscle contraction...think EXERCISE....What might one need for exercise or to DO WORK?

What organelle can provide cells of an organism with this?

• Golgi bodies

• Chloroplasts

• Mitochondria

• Lysosomes

Answer explanation

Mighty Mitochondria are like the motors of cars - they are the POWERHOUSE of cells because they provide cells with USABLE energy ATP through CELLULAR RESPIRATION

Which structures are used by a paramecium for maintaining water balance?

Hint: When in doubt REASON IT OUT

Would an organism be well off if water could flow out all at once like a faucet or would a pumping system be a better way to control the flow...?

• contractile vacuoles

• cilia

• pseudopodia

• food vacuoles

Answer explanation

When in doubt REASON IT OUT!

Wrong answers explained:

CILIA = hair-like projections that can be found in unicellular organisms like paramecia and humans.

-cilia can serve as filters

-cilia can help material or an organism move through a medium

-cilia in human ears are important in hearing

-cilia in human noses help filter germs and foreign bodies

Food vacuole - storing food is not going to help with the control of water movement throughout a cell and organism

Pseudopods are things amoeba can have

-pseudo = false

(like a pseudonym = false name)

-pod = foot