Question

1.Peroxisomes are single-membrane vesicles with high concentrations of catalase and urate oxidase. In a mutant lacking catalase, what is the most likely result in the cell?

a.the inability to break down glycogen

b.the inability to break down uric acid

c.the inability to breakdown fatty acids

d.the inability to breakdown accumulated peroxide

2.What is the action of the sodium-potassium pump?

Group of answer choices

a.Allows 2Na+ in, pumps 3K+ out

b.Allows 3Na+ in, pumps 2K+ out

c.Allows 2K+ in, pumps 3Na+ out

d.Allows 3K+ in, pumps 2Na+ out

3.The primary function of lysosomes is to

Group of answer choices

a.digest macromolecules, organelles, and microorganisms

b.be released and used as extracellular defense mechanisms.

c.produce ATP for the cell.

d.transport macromolecules to and from the nucleus.

4.Which of the following best describes the situation where membrane transport does NOT require a transporter?

Group of answer choices

a.The molecule to be transported is a small ion

b.The molecule to be transported is large and polar

c.The molecule to be transported is moved from a low to a high concentration

d.The molecule to be transported is small and non-polar

5.Which of the following is FALSE regarding mitochondria?

Group of answer choices

a.they possess an inner and an outer membrane

b.they have circular chromosomes

c.the NADH and FADH2 they use must be imported, as they do not produce any themselves

d.have their own ribosomes separate from the cellular ribosomes

6.The plant cell's central vacuole

Group of answer choices

a.provides the plant cell with support.

b.stores nutrients and cellular waste products.

c.is a reservoir for water.

d.All of the choices are correct

7.The process by which cholesterol is transported into the cell by the binding of LDL to its receptor and the internalization of the receptor-LDL complex is

Group of answer choices

a.facilitated transport.

b.active transport.

c.cotransport.

d.Endocytosis

If a sperm cell contains 16 chromosomes, it comes from an animal that has ______ chromosomes in its cells.

Group of answer choices

a.4

b.8

c.32

d.16

8.Chemiosmosis produces

Group of answer choices

achloroplast

b.mitochondria

c.ATP

d.gametes

9.A zygote formed from a human sperm and egg has 46 chromosomes but has Trisomy 21. The interpretation is that

Group of answer choices

a.The zygote has trisomy only

b.The zygote is said to have 3N number of chromosomes

c.The cell shows aneuploidy

d.None of the above

Answer 1

1. d. the inability to breakdown accumulated peroxide

Catalase enzyme is involved in the breakdown of hydrogen peroxide to oxygen and water. Catalase is present in the membrane bound organelle known as peroxisomes. Hydrogen peroxide, produced by various enzymatic reactions occurring in the peroxisomes, is harmful to the cell and hence is decomposed by the enzyme catalase present in the peroxisome.

2. c. Allows 2K+ in, pumps 3Na+ out

sodium-potassium pump is an ATP dependent, P-type ion pump. For every ATP that is hydrolysed, 2 potassium ions (K+) are pumped into the cell while 3 sodium ions (Na+) are pumped out of the cell. This is achieved via a change in the structure of the protein that acts as the transporter during the ATP hydrolysis. This creates both an electrical gradient and a concentration gradient across the cell membrane which is used for multiple purposes, one of them being transmission of nerve signals.

3. a. digest macromolecules, organelles, and microorganisms

Lysosomes are membrane bound organelles found in animal cells. Their primary function is to digest macromolecules, organelles, and microorganisms. They can process all types of biomolecules like protein, carbohydrates and nucleic acids. They have different types of acid hydrolase enzymes which are active only at the low pH of approximately 5. This low pH is maintained in the lysosome by a proton pump.

4. d. The molecule to be transported is small and non-polar

Small, non-polar molecules include oxygen and carbon dioxide which diffuse across cell membranes without the need for active transport. This happens in the lungs and heart where gas exchange occurs, when these molecules move from a region of higher concentration to a region of lower concentration via diffusion.

5. c. the NADH and FADH2 they use must be imported, as they do not produce any themselves

Mitochondria is membrane bound cell organelle found in most of the eukaryotic organisms. It is known as the powerhouse of the cell as it produces ATP through aerobic respiration. It has an outer membrane and an inner membrane which forms cristae to increase the surface area. Mitochondria is different from other cell organelles due the fact that it has its own DNA and ribosomes. The citric acid cycle occurs in the mitochondria during which NADH and FADH2 are generated to carry high energy electrons.

6. d. All of the choices are correct

All plant cells have central vacuoles and is made of cell sap and tonoplast. Cell sap is mostly made of water but it also has various other ingredients like nutrients, ions and even waste material which is stored to protect the integrity of the cell. The most important role of central vacuole is to maintain the turgor pressure of the cell thereby maintaining the shape of the plant cell.

7. d. Endocytosis

Low density lipoprotein (LDL) carries cholesterol through the bloodstream and enters cells through endocytosis, where receptors on the cell surface bind to the LDL and internalise it in a coated pit to form vesicles. These vesicles are taken to the lysosomes where the vesicle is degraded, releasing the cholesterol. This process is known as receptor-mediated endocytosis.

8. c. 32

A sperm cell ie the gamete cell always contains half the number of chromosomes as that of the parent cell. Thus, when a sperm cell and an ovum containing 16 chromosomes each fertilize, they form a diploid individual with 32 chromosomes.

9. c. ATP

Chemiosmosis is the process by which ions move across a membrane producing ATP. During this process ions move from a region of higher concentration to a region of lower concentration ie down an electrochemical gradient. In eukaryotic cells, chemiosmosis occurs in the mitochondria.