Science Test Revision Flashcards

Reliability and Measurement in Scientific Experiments

Reliability is defined as the degree to which repeated measurements are similar to one another or close to a calculated average. To verify the reliability of an experiment, the procedure should be repeated multiple times. An experiment is considered reliable if it yields consistent results upon repetition or if a sufficient number of samples have been collected to determine a stable average.

Techniques for environmental measurement require specific procedures to ensure accuracy. When measuring light intensity, the light-sensitive panel of the meter must be held at ground level and pointed directly toward the light source. It is critical to ensure that no shadows are cast over the panel while reading the scale. For measuring soil moisture, a probe is inserted into the soil to read the moisture levels on the scale. Between each reading, the probe must be wiped clean to prevent moisture from a previous measurement from contaminating or skewing subsequent results.

Ecosystem Components and Sampling Methodologies

An ecosystem is the combination of a habitat and a community. A habitat refers specifically to the places where an organism lives, while a community encompasses all the living things within that ecosystem. Various tools are used to monitor these environments. A pitfall trap allows for the capture, identification, and counting of ground-dwelling insects. For insects inhabiting trees and bushes, a pooter is used for capture and study.

Sampling of organisms is often conducted using transects or quadrats. A transect is employed to study gradual changes in the distribution of organisms across an ecosystem. A quadrat is used to estimate the abundance of plant species or slow-moving animal species. The distribution of organisms is heavily influenced by non-living abiotic factors, such as light intensity, temperature, and soil moisture, all of which are measured using dedicated probes and meters.

Vertebrate and Invertebrate Anatomy

Animals are broadly classified by their internal structures. Vertebrates possess an internal skeleton that provides support and protects vital organs. This skeleton also serves as an attachment point for muscles, facilitating movement. In contrast, invertebrates lack an internal skeleton. Some invertebrates derive their support and protection from a tough, crunchy external structure known as an exoskeleton.

Biodiversity and Ecological Conservation

Biodiversity refers to the variety of species in a given area. The health of an area is directly related to its biodiversity; higher species counts typically indicate a healthier ecosystem. For example, a forestry plantation generally exhibits low biodiversity, whereas a Caledonian forest exhibits high biodiversity. Maintaining high biodiversity is essential for providing raw materials, medicines, food, and chemicals for industry. It also supports ecological services such as pollination and water purification and preserves a gene pool necessary for breeding and conservation efforts. There is also an inherent ethical responsibility to maintain these systems.

Microscopy and Cellular Biology

A science revision session conducted on $24 \text{ Aug } 2026$ detailed the components and functions of the microscope. The eyepiece lens enlarges the image, while the objective lens provides further magnification. The stage holds the slides with the help of clips, and a light source sends illumination upward through the slide. The focusing dials move the stage closer to or further from the lens; the big focusing dial is used for major adjustments, and the fine focusing dial is used for sharp detail. The entire structure is supported by the arm, base, and stand.

Living organisms include animals, plants, fungi, and micro-organisms. Differences in cellular structure distinguish these groups. An animal cell consists of a nucleus, cytoplasm, and a cell membrane. A plant cell is more complex, containing a cell wall, nucleus, cell membrane, vacuole, cytoplasm, and chloroplasts.

Photosynthesis and Plant Physiology

Photosynthesis is the process by which plants produce nutrition. The chemical equation for this process is as follows: $\text{Water} + \text{Carbon Dioxide} \xrightarrow{\text{Light Energy}} \text{Food (Sugar)} + \text{Oxygen}$. The plant absorbs carbon dioxide and water and, by utilizing light energy, converts them into oxygen and glucose. There is a direct correlation between light and growth; as light intensity increases, the rate of photosynthesis also increases.

Agricultural Practices and Soil Management

Agriculture is the practice of farming, involving soil cultivation for growing crops and the rearing of animals for products like food and wool. Because the human population is increasing rapidly, there is a constant need to produce more food. Methods used to increase yield include the application of fertilizers, pesticides, genetically modified (GM) crops, biological control, and organic farming techniques.

Fertilisers are chemicals added to soil to improve crop yields by replacing nutrients lost during plant growth and harvesting. These can be natural, such as manure, or artificial, such as factory-produced chemicals. Fertilisers must be soluble so they can dissolve in water and be absorbed by plant roots. However, if a fertiliser is too soluble, it may be washed away before the plant can utilize it. Essential nutrients in fertilisers include Nitrogen (N), Phosphorus (P), and Potassium (K). For example, a mixture containing $10\,kg$ of Nitrogen, $5\,kg$ of Phosphorus, and $15\,kg$ of Potassium represents an NPK ratio of $10:5:15$, which simplifies to a ratio of $2:1:3$.

Biological Classification and Animal Diversity

Classification helps organize the animal kingdom into manageable groups. Major groups include:

• Fish: Cold-blooded animals that live in water, breathe through gills, use the environment to regulate temperature, and have fins, scales, and are born from eggs.
• Reptiles: Cold-blooded animals with scales and ear holes that lay eggs. They move using $4$ legs or no legs and are known to live longer than many other animals.
• Birds: Warm-blooded animals with features such as wings and feathers. They have $2$ legs, ear holes, and lay eggs.
• Amphibians: Cold-blooded animals with moist skin that live on both land and water. They lay jelly-like eggs and undergo metamorphosis during their growth stages.
• Mammals: Warm-blooded animals with hair or fur. They can live on land or in the water, and some possess the ability to fly. Mammals, including humans, give birth to live young from the mother's womb.