D2 (Cell & nuclear division, Gene expression, water potential)

Question 1

Cell & Nuclear Division.

Mitosis

Answer 1

Definition: Cell division resulting in two genetically identical daughter cells.

Question 2

Cell & Nuclear Division.

Meiosis

Answer 2

Definition: Cell division producing haploid gametes with genetic variation.

Question 3

Cell & Nuclear Division.

Crossing Over

Answer 3

Description: Exchange of genetic material between homologous chromosomes during meiosis.

Question 4

Explain how mitosis contributes to growth, repair, and asexual reproduction.

Answer 4

The process of mitosis generates new cells that are genetically identical to each other.

Mitosis helps organisms grow in size and repair damaged tissue.

Question 5

Compare mitosis and meiosis, emphasizing genetic diversity.

Answer 5

Mitosis builds a person with an identical set of chromosomes in every cell.
Meiosis generates reproductive cells with new combinations of gene variations.

Meiosis leads to genetic diversity

Question 6

Explain the role of mitosis in a multicellular organism.

Answer 6

Mitosis contributes to growth by producing new cells, facilitates tissue repair, and is involved in asexual reproduction for organisms like plants.

Question 7

Gene Expression.

Transcription

Answer 7

Process: Synthesis of mRNA from a DNA template.

Question 8

Gene Expression

Translation

Answer 8

Process: Synthesizing a polypeptide chain from mRNA using ribosomes.

Question 9

Gene Expression.

Operon

Answer 9

Definition: A unit of genetic material that controls gene expression in prokaryotes.

Significance: Allows coordinated regulation of multiple genes.

Question 10

Explain how mRNA is formed

Answer 10

RNA polymerase joins the RNA nucleotides together via condensation reactions that result in the formation of the phosphodiester bonds. Pre-mRNA is then spliced to remove introns before it is ready for translation.

Question 11

Elaborate on the role of tRNA and the significance of codons and anticodons.

Answer 11

Codons: complementary nucleotide base of the DNA sequence found in mRNA molecule
Anticodon: complementary nucleotide base of codon located in the tRNA arm.

The codon and anticodon work together to bring desired amino acids.

Question 12

Explain the processes of transcription and translation.

Answer 12

Transcription involves the synthesis of mRNA from DNA, mediated by RNA polymerase.

Translation is the synthesis of a polypeptide chain from mRNA using ribosomes, with tRNA bringing amino acids according to codons.

Question 13

Water Potential.

Define the term water potential

Answer 13

The measure of the potential energy of water in a particular environment.

Question 14

Water Potential.

Define the term Osmosis

Answer 14

Movement of water across a selectively permeable membrane.

Question 15

Water Potential.

Define the term Turgor Pressure

Answer 15

Pressure exerted by the cell contents against the cell wall.

Significance: Maintains cell rigidity in plant cells.

Question 16

What are factors affecting water potential.

Answer 16

pressure, concentration of solutes and gravity

Question 17

What is the role of aquaporins in facilitating osmosis.

Answer 17

transport water across cell membranes in response to osmotic gradients created by active solute transport.

Question 18

Define water potential and explain the significance of turgor pressure in plant cells

Answer 18

Water potential measures water’s potential energy, influenced by solute potential and pressure potential. Turgor pressure in plant cells maintains cell rigidity, preventing wilting.

Question 19

Checkpoints in Cell Cycle

Answer 19

Points in the cell cycle where regulatory proteins assess the cell’s readiness to proceed.

surveillance mechanisms that monitor the order, integrity, and fidelity of the major events of the cell cycle. These include growth to the appropriate cell size, the replication and integrity of the chromosomes, and their accurate segregation at mitosis.

Question 20

Cyclins and Cyclin-Dependent Kinases

Answer 20

Description: Proteins regulating the cell cycle by controlling progression through checkpoints.

Significance: Ensures orderly cell cycle progression.

Question 21

Explain the significance of checkpoints in the cell cycle and how cyclins and CDKs regulate these checkpoints.

Answer 21

Checkpoints ensure accurate cell division. Cyclins and CDKs control checkpoints by activating specific proteins, regulating cell cycle progression.

Question 22

Epigenetics

Answer 22

Modifications to DNA that affect gene expression without altering the DNA sequence.

Significance: Influences cellular differentiation and response to environmental factors.

Question 23

Describe the concept of epigenetics and how RNA interference can be utilized in the regulation of gene expression.

Answer 23

Epigenetics involves modifications to DNA influencing gene expression without altering the sequence. RNA interference inhibits gene expression by degrading or preventing mRNA translation, potentially treating genetic disorders.

Question 24

Plasmolysis

Answer 24

Description: Contraction of the protoplast of a plant cell due to water loss.

Consequence: Loss of turgor pressure.

Question 25

Define solute potential and explain the process of plasmolysis in plant cells.

Answer 25

Solute potential is the contribution of solutes to water potential. Plasmolysis is the contraction of plant cell protoplast due to water loss, leading to the loss of turgor pressure.