Explore Life Sciences: Grade 8 Biology Quiz

Photosynthesis is a process in which plants use sunlight, carbon dioxide, and water to produce glucose and oxygen. Therefore, photosynthesis can only occur if there is light available for the plants to capture and convert into energy. In the absence of light, such as during the night, photosynthesis cannot take place. Hence, the correct answer is "if there is light".

The function of xylem is to transport water and minerals. Xylem is a type of vascular tissue in plants that is responsible for conducting water and nutrients from the roots to the rest of the plant. It consists of specialized cells called tracheids and vessel elements that form long tubes, allowing for the efficient movement of water and minerals throughout the plant. This process is essential for the plant's survival as it provides the necessary hydration and nutrients needed for growth and metabolism.

Oxygen is one of the substances produced by photosynthesis. During the process of photosynthesis, plants use sunlight, water, and carbon dioxide to produce glucose (a type of sugar) and oxygen. The oxygen is released into the atmosphere as a byproduct of photosynthesis and is essential for the survival of many living organisms, including humans.

The correct answer is the evaporation of water in the leaf. Transpiration is the process by which water is lost from the leaves of plants through small openings called stomata. These stomata allow water to evaporate from the leaf surface, creating a concentration gradient that pulls water up from the roots through the xylem vessels. This process is essential for the plant's water uptake, nutrient transport, and cooling. It also helps maintain the plant's shape and structure.

In a photosynthesis experiment, the gas bubbles produced by pond weed indicate the release of oxygen. During photosynthesis, plants use sunlight, water, and carbon dioxide to produce glucose and oxygen. The oxygen is a byproduct of this process and is released into the surrounding environment in the form of gas bubbles. Therefore, the correct answer is oxygen.

Vascular bundles in plants consist of xylem and phloem. Xylem is responsible for transporting water and minerals from the roots to the rest of the plant, while phloem transports sugars and other organic compounds from the leaves to other parts of the plant. These two tissues work together to ensure the proper functioning and growth of the plant.

Living organisms undergo changes throughout their life cycle, whether it's growth, development, or adaptation to their environment. This ability to change and respond to internal and external cues is a fundamental characteristic of life. The other options are all key traits of living organisms.

Boiling the leaf in photosynthesis experiments would serve the purpose of killing any pathogens present on the leaf. This step is important to ensure that the results of the experiment are not influenced by any potential diseases or infections that could affect the photosynthesis process. By eliminating pathogens, the experiment can focus solely on studying the effects of photosynthesis without any interference.

The function of phloem is to transport the result of photosynthesis. Phloem is a vascular tissue in plants responsible for the transportation of organic nutrients, such as sugars and amino acids, produced during photosynthesis. These nutrients are transported from the leaves, where photosynthesis occurs, to other parts of the plant, such as the roots, stems, and fruits, where they are needed for growth, energy production, and storage. This transportation is essential for the overall functioning and survival of the plant.

Root pressure is one of the factors that influence the absorption of water and mineral salts in plants. Root pressure refers to the force created by the active transport of ions into the root cells, which causes water to move into the roots and up the xylem vessels. This pressure helps to push water and nutrients upwards from the roots to the rest of the plant. Therefore, root pressure plays a crucial role in the absorption and transportation of water and minerals in plants.

Water and mineral salts can be absorbed by roots easily due to a combination of root pressure, stem capillarity, and transpiration pull. Root pressure refers to the force created by the active pumping of ions into the root cells, which increases the water potential and drives water uptake. Stem capillarity allows water to move upwards through tiny tubes in the stem, aided by adhesive and cohesive forces. Transpiration pull is caused by the evaporation of water from the leaves, creating a negative pressure that pulls water upwards from the roots. These three mechanisms work together to facilitate the efficient absorption and transport of water and minerals in plants.

The correct answer is "show that product of photosynthesis is amylum". This is because amylum, also known as starch, is one of the main products of photosynthesis in plants. During photosynthesis, plants use sunlight, carbon dioxide, and water to produce glucose, which is then converted into starch for storage purposes. Therefore, conducting experiments to show the presence of amylum in plants would provide evidence of the product of photosynthesis.

The function of lugol is to test for the presence of amylum in the leaf. Lugol is a solution that contains iodine, which reacts with starch (amylum) to form a blue-black color. By applying lugol to the leaf, John can determine if there is starch present, indicating that photosynthesis has occurred.

The Casparian strip is a specialized structure found in the endodermis of plant roots. It is made up of a waterproof material called suberin, which prevents water from moving freely through the cell walls of the endodermal cells. This strip forces water and solutes to pass through the selectively permeable plasma membranes of the endodermal cells, allowing the plant to control the uptake of water and nutrients from the soil. In this way, the Casparian strip acts as a barrier to regulate the movement of water and ions into the vascular tissues of the plant.

Rigid xylem is the correct answer because the rigidity of the xylem vessels allows them to withstand the pressure exerted by the water as it moves upwards through the plant. The rigid walls of the xylem vessels prevent them from collapsing under the tension created by the transpiration pull, thus facilitating the movement of water from the roots to the leaves.

Mineral salt is one of the substances needed for the process of photosynthesis. It provides essential nutrients and minerals to the plant, which are required for the synthesis of organic compounds during photosynthesis. Without mineral salts, plants would not be able to produce glucose, oxygen, and other necessary compounds for their growth and survival.

Plasmodesmata are small channels that connect plant cells, allowing for the movement of water and other substances between cells. These channels are made up of cytoplasmic strands that pass through the cell walls of adjacent cells, creating a continuous pathway for the flow of water and solutes. Therefore, plasmodesmata facilitate the movement of water from one cell to another within the plant.

Alcohol functions by loosening chlorophyll. Chlorophyll is responsible for the green color in plants and plays a crucial role in photosynthesis. When alcohol is applied to plants, it breaks down the chlorophyll molecules, causing the green color to fade. This process is often used in laboratory experiments or research to remove chlorophyll and study other plant pigments or compounds.

In the root, water can enter the xylem without crossing cell membranes through a pathway called the apoplast. The apoplast pathway refers to the movement of water through the cell walls and intercellular spaces of the root, bypassing the cell membranes. This pathway allows for efficient water transport in plants. Symplast refers to the movement of water through the cytoplasm of plant cells, casparian strip is a waterproof barrier in the endodermis that forces water to cross cell membranes, and plasmodesmata are channels that connect plant cells and allow for communication and transport between them.

The root cap is responsible for protecting the apical meristem, which is the growing tip of the root. The apical meristem is a delicate and important part of the root that is responsible for the growth and development of the root. The root cap acts as a barrier, shielding the apical meristem from damage as the root pushes through the soil. It also helps in detecting gravity, allowing the root to grow downwards. Therefore, the function of the root cap is to protect the apical meristem.