Standard Seven General Science Review

Comprehensive practice flashcards covering Standard Seven General Science lecture notes, including biology, physics, chemistry, and environmental science concepts.

What are adaptations?

Gradual changes that occur in the body parts and behavior of organisms which help them to adjust to their surroundings over a long period of time.

In desert plants, why is the stem fleshy and green?

The stem stores water and food, making it fleshy, and it is green because it performs photosynthesis in the absence of leaves.

What is the difference between tap roots and fibrous roots?

Tap roots consist of a primary root that grows into the ground with secondary roots (found in dicotyledonous plants), while fibrous roots are thread-like or fibre-like roots arising from the stem (found in monocotyledonous plants).

What are the two principles of Darwin’s theory of evolution?

1. Survival of the fittest (organisms best adapted to a changing environment are likely to survive) and 2. Natural selection (beneficial changes are preserved in the next generation).

How is the scientific name of an organism assigned in binomial nomenclature?

The name consists of two parts: the first part is the 'genus' and the second part is the 'species'.

What is the function of the root cap?

It is a cap-like structure that protects the delicate root-tip from injuries during growth.

Define the parts of a leaf: Lamina, Petiole, and Stipules.

The lamina is the broad, spread-out leaf-blade; the petiole is the stalk connecting the leaf to the stem; and stipules are small leaf-like structures near the leaf-base.

In flowers, what are the androecium and gynoecium?

The androecium is the male reproductive part (consisting of stamens, anthers, and filaments), and the gynoecium is the female reproductive part (consisting of carpels, stigmas, styles, and ovaries).

State Bernoulli’s principle regarding air pressure.

The pressure of air decreases when its velocity increases, and the pressure of air increases when its velocity decreases.

What is the 'scattering of light'?

A natural phenomenon where fine particles of gases, dust, smoke, and moisture in the air spread light rays in all directions.

What is the 'anomalous behavior' of water?

Water reaches its maximum density at $4^\circ C$; if cooled further, its density decreases and its volume increases, causing it to expand.

Identify the three soil types based on texture and their primary characteristic.

1. Sandy soil (large particles, drains rapidly); 2. Silt soil (medium particles, high nutrient capacity); 3. Clay soil (small particles, high water holding capacity).

What is the chemical equation for Photosynthesis?

$$6CO_2 + 6H_2O \xrightarrow{\text{Sunlight/Chlorophyll}} C_6H_{12}O_6 + 6O_2$$

Compare the functions of Xylem and Phloem in plant transport systems.

Xylem transports minerals and water from the roots to all aerial parts; Phloem transports food (glucose) from the leaves to other parts of the plant.

What is symbiotic nutrition, and what is a common example?

A relationship where two or more types of plants live together to fulfill needs like nutrition and protection; an example is Lichen (symbiosis between algae and fungi).

Define 'saprophyte' plants.

Plants that obtain food from dead and decaying bodies of other organisms, such as mushrooms and yeast.

What is the difference between a scalar quantity and a vector quantity?

A scalar quantity is expressed by magnitude alone (e.g., mass, area), while a vector quantity requires both magnitude and direction (e.g., displacement, velocity).

State the formula and SI unit for Work.

The formula is $Work (W) = Force (F) \times Displacement (s)$; the SI unit is the Joule ($J$).

Define Newton’s First Law of Motion.

If no force is acting on a body, its velocity does not change; a stationary body remains stationary, and a moving body continues with the same velocity and direction.

What is the purpose of a gold leaf electroscope?

It is a simple device used to detect the presence of an electric charge on an object.

Identify the three modes of heat transfer.

1. Conduction (through solids, requires a medium); 2. Convection (through liquids and gases, requires a medium); 3. Radiation (does not require a medium).

Who made the first thermos flask, and what is its scientific name?

Sir James Dewar; it is also called a Dewar flask.

What are the five steps of nutrition in animals?

1. Ingestion, 2. Digestion, 3. Absorption, 4. Assimilation, and 5. Egestion.

How does the process of Pasteurization protect food?

It involves heating a liquid (like milk) to a specific temperature (e.g., $80^\circ C$ for $15$ minutes) and cooling it quickly to destroy microbes.

What is the difference between a total solar eclipse and a partial solar eclipse?

A total solar eclipse occurs when the moon completely covers the solar disc; a partial eclipse occurs when the disc is only partially covered.

Define 'Infrasonic' and 'Ultrasonic' sound.

Infrasonic sound has a frequency less than $20\,Hz$; ultrasonic sound has a frequency higher than $20,000\,Hz$.

What is the unit of frequency, and what does it measure?

The unit is Hertz ($Hz$); it measures the number of oscillations per second.

Distinguish between voluntary and involuntary muscles.

Voluntary muscles depend on our will (e.g., arms, legs), whereas involuntary muscles carry out vital functions without our conscious control (e.g., heart, stomach).

Which enzyme is found in saliva, and what is its function?

Ptyalin (salivary amylase); it converts starch into a sugar called maltose.

What are the characteristics of a physical change?

The properties and composition of the original substance remain the same, and no new substance is formed.

What is an 'element' in scientific terms?

A substance whose molecules are made of one or more atoms that are exactly alike and cannot be decomposed into different substances.

Define 'Distillation'.

A method used to separate the components of a mixture of a liquid and a soluble solid, or to purify impure liquids by boiling and then condensing the vapour.

What are the components of LPG (Liquified Petroleum Gas)?

It contains mainly propane and butane in a ratio of $30:70$.

How are magnetic lines of force defined?

Imaginary lines that run from the north pole to the south pole of a magnet, used to represent the magnetic field and its intensity.

What is the definition of a 'Constellation'?

A group of stars occupying a small portion of the celestial sphere that appears to form figures like animals, humans, or objects.

Define 'Zenith' and 'Nadir' in the context of the celestial sphere.

Zenith is the point on the celestial sphere exactly above the observer's head; Nadir is the point exactly below the observer's feet.