AZSCI Life Science 1 — Questions and Answers
Question 1: Which organelle in plant cells is responsible for photosynthesis?
- Nucleus
- Mitochondrion
- Chloroplast (Correct answer)
- Ribosome
Correct answer: Chloroplast
Chloroplasts are specialized organelles found in plant cells that contain the green pigment chlorophyll. This chlorophyll absorbs sunlight, which provides the energy needed to convert carbon dioxide and water into glucose (food) and oxygen through the process of photosynthesis. This makes chloroplasts essential for plant survival and the base of most food chains.
Question 2: What is the basic unit of heredity?
- Gene (Correct answer)
- Cell
- Protein
- Chromosome
Correct answer: Gene
A gene is a fundamental unit of heredity, consisting of a specific sequence of DNA or RNA. Genes carry the instructions for building proteins or functional RNA molecules, which in turn determine an organism's traits and characteristics. These units are passed from parents to offspring, dictating inherited features.
Question 3: Which of the following best describes the function of the circulatory system in the human body?
- Breaks down food for absorption
- Transports oxygen, nutrients, and wastes throughout the body (Correct answer)
- Protects the body from infections
- Regulates body temperature
Correct answer: Transports oxygen, nutrients, and wastes throughout the body
The circulatory system, composed of the heart, blood vessels, and blood, is responsible for the vital transport of substances throughout the body. It delivers oxygen from the lungs and nutrients from digested food to all cells, while simultaneously collecting metabolic waste products like carbon dioxide to be expelled. This continuous circulation is crucial for maintaining cellular function and overall health.
Question 4: What is the process by which organisms with favorable traits are more likely to survive and reproduce?
- Mutation
- Evolution
- Natural selection (Correct answer)
- Genetic drift
Correct answer: Natural selection
Natural selection is a core mechanism of evolution, proposed by Charles Darwin. It describes the process where organisms better adapted to their environment tend to survive and produce more offspring than those less adapted. Over generations, this leads to an increase in the frequency of advantageous traits within a population, driving evolutionary change.
Question 5: Which of the following is an example of a producer in an ecosystem?
- Deer
- Mushroom
- Grass (Correct answer)
- Eagle
Correct answer: Grass
Producers are organisms that create their own food, typically through photosynthesis, forming the base of an ecosystem's food web. Grass, like all plants, uses sunlight to convert carbon dioxide and water into energy-rich organic compounds. This ability to produce its own food makes grass a primary producer, supporting all other trophic levels.
AZSCI Life Science 1
Which organelle in plant cells is responsible for photosynthesis?