Cellular Processes and Disease

This page delves deeper into cellular processes, focusing on diffusion, digestion, and photosynthesis, as well as discussing infectious diseases and immune responses.

The page begins by explaining diffusion and osmosis:

Example: Diffusion is described as the movement of particles from a high concentration to a low concentration through a semi-permeable membrane.

The text then moves on to discuss digestion, mentioning enzymes and their role in breaking down food molecules.

Photosynthesis is covered next, with a focus on practical experiments:

Highlight: The rate of photosynthesis can be measured by counting oxygen bubbles released from pond weed or by monitoring light absorption.

The page then shifts to infectious diseases:

Definition: Infectious diseases are caused by pathogens, which can be bacteria, viruses, fungi, or protists.

The body's defense mechanisms against pathogens are described in detail:

Vocabulary: White blood cells, including phagocytes and lymphocytes, play crucial roles in the immune response. Phagocytes engulf pathogens, while lymphocytes produce antibodies.

The text explains that antibodies are complementary to specific pathogen antigens and can take time to find a match. However, the immune system remembers pathogens, making future responses faster.

The page concludes with a brief mention of penicillin, discovered by Fleming, and the process of developing new medicines, including discovery, development, testing, and trials.

Practice Questions and Additional Information

This page provides practice questions and additional information on various topics covered in the previous pages.

The page starts with a diagram of a cell, asking students to identify specific structures:

Example: Students are asked to identify the nucleus in the cell diagram and explain why the cell is a plant cell (due to the presence of a cell wall).

The text then moves on to questions about white blood cells and their role in defending the body against pathogens:

Highlight: White blood cells defend the body by engulfing pathogens and producing antibodies.

There's a question about the decrease in the number of measles cases, suggesting that vaccination has played a role in this reduction.

The page includes information about sperm cells, noting that they have many mitochondria to provide energy for movement.

A section on photosynthesis is included, presenting the chemical equation:

Quote: "6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (light energy)"

The page concludes with additional questions and information:

• A calculation of cell size using magnification formulas
• A comparison of electron microscopes and light microscopes, noting that electron microscopes have higher resolution
• A question about the breakdown of carbohydrates during digestion, introducing the enzyme amylase

Vocabulary: Amylase is an enzyme that breaks down carbohydrates during digestion.

This page serves as a review and application of the concepts covered in the previous pages, helping students to reinforce their understanding of key biological processes.

Cell Structure and Types

This page covers the fundamental aspects of cell biology, focusing on the differences between plant and animal cells, as well as eukaryotic and prokaryotic cells.

The page begins by outlining the key components of animal and plant cells. Animal cells are described as having a membrane, nucleus, cytoplasm, mitochondria (for respiration), and ribosomes (for protein synthesis). Plant cells are noted to have additional structures such as vacuoles (for sap storage), chloroplasts (for photosynthesis), and a cell wall.

Definition: Eukaryotic cells are defined as having DNA contained within a nucleus, while prokaryotic cells (such as bacteria) do not have a nucleus and their DNA is free in the cytoplasm.

The page then moves on to discuss cell division processes:

Highlight: Meiosis and mitosis chromosome processes are crucial for cell reproduction and genetic diversity.

Mitosis is described as the process of cell division where chromosomes are copied. It's noted that humans have 23 pairs of chromosomes, totaling 46.

Meiosis is explained as the process for creating sex cells (gametes). This process involves DNA copying, crossing over, and two divisions, resulting in daughter cells or egg/sperm cells.

The page concludes with information on microscopy and DNA:

Vocabulary: Microscopy techniques mentioned include SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy).

DNA is described as being made up of four bases (chemicals): T+A and C+G. The page explains that every three bases code for an amino acid, which tells the cell the order for protein synthesis.