Basic 5 Integrated Science

Explanation
The hard outer covering of a seed is called the testa. It serves as a protective layer for the embryo inside the seed, shielding it from external damage and providing support during germination. The testa is often thick and durable, helping to prevent dehydration and providing resistance to mechanical stress. It also acts as a barrier, preventing pathogens and pests from entering the seed. Overall, the testa plays a crucial role in ensuring the survival and successful germination of the seed.

Explanation
Chlorophyll is the correct answer because it is the green pigment found in plants that is responsible for absorbing light energy during photosynthesis. It is essential for the process of converting sunlight into chemical energy, which is used by plants to produce glucose and oxygen. Stomata are the small openings on the surface of leaves that regulate gas exchange, while starch is a carbohydrate used for energy storage in plants. Mineral salts are essential nutrients for plant growth, but they do not refer to the green pigment in plants.

Explanation
Exhaled air primarily consists of carbon dioxide, as it is the waste product of cellular respiration. When we inhale, we take in oxygen, which is used by our cells for various metabolic processes. As a result, carbon dioxide is produced and needs to be expelled from the body. Oxygen, nitrogen, and hydrogen are also present in the air we breathe, but they are not the main components of exhaled air.

Explanation
Germination is the correct answer because it refers to the process by which a seed begins to grow and develop into a seedling. During germination, the seed absorbs water and swells, causing the outer seed coat to split. This allows the embryonic plant inside to emerge and start growing roots, stems, and leaves. Germination is an essential step in the life cycle of a plant, as it marks the transition from a dormant seed to an actively growing seedling.

Explanation
Air is a mixture of gases because it is composed of various gases such as nitrogen, oxygen, carbon dioxide, and trace amounts of other gases. These gases are not chemically combined but exist together in the atmosphere.

Explanation
The petiole is the part of a plant that holds the leaf blade to the direction of the sun. It is a slender stalk that connects the leaf blade to the stem, allowing the leaf to be positioned optimally for maximum sunlight absorption. The petiole also provides support and flexibility to the leaf, allowing it to adjust its position and orientation to capture sunlight efficiently for photosynthesis.

Explanation
Cotton seeds have a fluffy structure that allows them to be easily carried by the wind. This is known as wind dispersal. As the wind blows, it catches onto the fibers of the cotton seed and carries it away, helping to spread the seeds over a wider area. This method of dispersal increases the chances of the seeds finding suitable conditions for germination and growth.

Explanation
Dispersion refers to the scattering or spreading of fruits and seeds away from their parent plants. This process is essential for the survival and reproduction of plants as it allows for the colonization of new areas and reduces competition among offspring. Through various mechanisms such as wind, water, animals, or self-ejection, fruits and seeds are dispersed to different locations where they can germinate and grow into new plants.

Explanation
Seeds require oxygen for germination as it is essential for respiration to occur. During germination, the seed absorbs water and begins to break down stored food reserves. This process requires energy, which is produced through respiration. Oxygen is necessary for this respiration process to take place, allowing the seed to grow and develop into a new plant. Without sufficient oxygen, the seed would not be able to carry out respiration and germination would be inhibited.

Explanation
Respiration is the correct answer because it refers to the process of breaking down food substances like glucose and glycerol in living cells to release energy. This process can occur with or without the presence of oxygen. Digestion is the process of breaking down food in the digestive system, excretion is the elimination of waste products, and nutrition refers to the intake and utilization of nutrients.