Science Flashcards

The very hard greenish-black coating around the edges of your teeth is known as

Answer: plaque

Plaque is a sticky, colorless film of bacteria that constantly forms on your teeth. If not removed regularly through brushing and flossing, plaque can harden into tartar (calculus), which absorbs stains and can appear greenish-black, especially around the gum line and tooth edges. This hardened plaque is what the question describes.

The technique of limiting the number of seedlings per stand to improve development is known as

Answer: thinning out.

Thinning out is a horticultural practice where excess or weaker seedlings are removed from a group. This technique is used to reduce competition among plants for resources like light, water, and nutrients, thereby improving the growth and development of the remaining, stronger seedlings.

Which of the following electrical components is not built from semiconductors?

Answer: Capacitor

Semiconductors are materials like silicon and germanium that are fundamental to modern electronic components due to their unique electrical properties. LEDs, Transistors, and Diodes are all semiconductor devices that rely on the properties of p-n junctions. A capacitor, however, is a passive component that stores electrical energy in an electric field between two conductive plates separated by a dielectric (insulating) material, and its operation does not inherently rely on semiconductor materials.

Which of the following bodily forms allows fluid to travel most easily?

Answer: Streamline

A streamline shape is designed to offer the least resistance to fluid flow, whether it's liquid or gas. Objects with streamlined forms, like fish, birds, or aircraft wings, allow the fluid to flow smoothly around them with minimal turbulence. This characteristic enables them to move through fluids most easily and efficiently compared to other shapes like triangular, rectangular, or spherical.

One advantage of technology for industrialization is

Answer: provision of equipment.

When a ray of light passes from a less dense medium (like air) to a denser medium (like water or glass), it slows down. This change in speed causes the light ray to bend towards the normal, which is an imaginary line perpendicular to the surface at the point where the light enters the new medium. Conversely, when light goes from a denser to a less dense medium, it bends away from the normal.

The element utilized in the production of electronic components is

Answer: silicon.

Silicon is a semiconductor element that is extensively used in the electronics industry. Its unique electrical properties make it ideal for manufacturing transistors, integrated circuits, microprocessors, and other essential electronic components. It forms the foundation of most modern electronic devices.

When a ray of light goes from a dense medium to a denser medium, it

Answer: bends towards the normal.

One of the most significant advantages of technology for industrialization is the provision of advanced equipment and machinery. These technological tools enable automation, increase production efficiency, improve product quality, and allow for mass production, all of which are crucial for industrial growth and development.

Which of the following factors has the biggest impact on vegetable crop yield?

Answer: Source of water

Water is an absolutely essential resource for the growth and survival of all plants, including vegetable crops. It is vital for photosynthesis, nutrient transport, and maintaining turgor pressure. Without an adequate and reliable source of water, vegetable crops cannot grow or produce a yield, making it the factor with the biggest impact on crop yield.

Which of the following mixtures may best be separated using a separating funnel?

Answer: Sulphur and water

A separating funnel is specifically designed to separate immiscible liquids, which are liquids that do not mix and form distinct layers due to differences in density. Water and vegetable oil are classic examples of immiscible liquids, with oil floating on top of water, allowing them to be easily separated by draining the denser water layer from the bottom. Sulphur is a solid and would typically be separated from water by filtration or decantation, not a separating funnel, which is for liquid-liquid separation.

The planet that shines the brightest is

Answer: Venus

Venus is often referred to as the 'Morning Star' or 'Evening Star' because it is the brightest planet visible from Earth. Its extreme brightness is due to its thick, highly reflective atmosphere, which efficiently scatters sunlight back into space. This makes it easily observable and exceptionally luminous in the night sky.

The following changes are caused by soil erosion, except

Answer: growth in bushfires.

Soil erosion involves the displacement of the top layer of soil, leading to several detrimental effects such as loss of essential nutrients for plants, weakening of plant support systems, and undermining of building foundations. However, soil erosion is not a direct cause of an increase in bushfires; bushfires are typically caused by factors like dry conditions, lightning, or human activity, although they can in turn contribute to erosion.