Topic 1 Key Concepts in Biology

Question 1

Name the structures found in both animal and plant cells.

Answer 1

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.

Question 2

What additional structures are found in plant cells but not in animal cells?

Answer 2

Cell wall, chloroplasts, and a permanent vacuole

Question 3

What is the function of the mitochondria?

Answer 3

The site of aerobic respiration, where energy is released from glucose.

Question 4

What is the function of ribosomes?

Answer 4

To synthesize proteins by joining amino acids together.

Question 5

What is the formula for magnification?

Answer 5

Magnification = Image size ÷ Actual size.

Question 6

Which type of microscope has a higher resolution, and why?

Answer 6

Electron microscopes, because they use electron beams that have shorter wavelengths than light, providing more detailed images.

Question 7

What are the two main types of microscopes used to study cells?

Answer 7

Light microscope and electron microscope.

Question 8

What is the main disadvantage of electron microscopes compared to light microscopes?

Answer 8

Electron microscopes cannot be used to view living specimens, as the samples must be placed in a vacuum.

Question 9

What is an enzyme?

Answer 9

A biological catalyst that speeds up chemical reactions in the body without being used up.

Question 10

What is the active site of an enzyme?

Answer 10

The region on the enzyme where the substrate binds and the reaction takes place.

Question 11

How does temperature affect enzyme activity?

Answer 11

Increasing temperature increases enzyme activity up to the optimum temperature, but beyond this, the enzyme denatures, reducing its activity.

Question 12

How does pH affect enzyme activity?

Answer 12

Each enzyme has an optimum pH; deviations from this can cause the enzyme to denature, reducing its activity.

Question 13

What is diffusion?

Answer 13

The movement of particles from an area of high concentration to an area of low concentration.

Question 14

What is osmosis?

Answer 14

The movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.

Question 15

What is active transport, and how is it different from diffusion?

Answer 15

Active transport moves particles against the concentration gradient (from low to high concentration), requiring energy from respiration, unlike diffusion.

Question 16

Give an example of where active transport occurs in plants.

Answer 16

In root hair cells, where minerals are absorbed from the soil.

Question 17

What are the three main types of biological molecules?

Answer 17

Carbohydrates, proteins, and lipids.

Question 18

What are carbohydrates made of?

Answer 18

Simple sugars like glucose.

Question 19

What are proteins made of?

Answer 19

Amino acids.

Question 20

What is the test for starch?

Answer 20

The iodine test – starch turns iodine from brown/orange to blue-black.

Question 21

How do you test for glucose in a solution?

Answer 21

By using Benedict’s solution; it turns from blue to brick-red when heated if glucose is present.

Question 22

What is the structure of DNA?

Answer 22

DNA has a double helix structure made up of two strands of nucleotides.

Question 23

What are the four bases of DNA, and how do they pair?

Answer 23

Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).

Question 24

What is the role of DNA in a cell?

Answer 24

DNA contains the genetic instructions for the development, functioning, growth, and reproduction of all living organisms.

Question 25

How is a gene related to a protein?

Answer 25

A gene is a segment of DNA that codes for a specific protein by determining the sequence of amino acids.