Osmosis and Animal Cells

This page introduces the concept of osmosis and its effects on animal and plant cells.

Osmosis is defined as the movement of water from a higher water concentration to a lower concentration through a partially permeable membrane. The page explains how this process affects different types of cells:

Definition: Osmosis is the movement of water from a higher water concentration to a lower concentration through a partially permeable membrane.

• Animal cells:

  • Can burst in dilute solutions
  • Can shrink in concentrated solutions
  • Lack a cell wall to prevent swelling or shrinking

• Plant cells:

  • Have a cell wall allowing them to swell without bursting
  • Become turgid (swollen) in dilute solutions
  • Become sunken in concentrated solutions

Vocabulary: Turgid - A term used to describe swollen plant cells in dilute solutions.

The page also mentions that the cytoplasm of cells is a relatively concentrated solution with a low concentration of water. When placed in water, osmosis occurs, causing water to move from outside to inside the cell.

Example: If a cell is placed in water, osmosis will cause water to move from outside the cytoplasm into the cell.

The page concludes with some review questions to reinforce understanding of key concepts related to osmosis in animal cells.

Organic Chemistry: Alkenes and Their Properties

This page delves into organic chemistry, focusing on alkenes and their properties, which is a crucial topic in GCSE Chemistry.

The page begins by introducing crude oil:

Definition: Crude oil is a fossil fuel formed mostly from dead sea creatures (e.g., plankton). It is the source of many fuels and other chemicals such as plastic.

Crude oil is described as a mixture of hydrocarbons, compounds made up of only hydrogen and carbon atoms. The page then focuses on alkenes, a group of hydrocarbons found in crude oil.

Key points about alkenes include:

1. They are made up of a chain of carbon atoms with as many hydrogen atoms bonded as possible.
2. Their general formula is CnH2n+2, where n is the number of carbon atoms.
3. The properties of alkanes change with the number of carbon atoms in the molecule.

The page provides structural formulas and names for several alkenes, including ethene, propene, and different forms of butene.

Example: Ethene (C2H4) and propene (C3H6) are examples of alkenes with different numbers of carbon atoms.

The document also discusses the combustion of hydrocarbons:

• Complete combustion occurs when hydrocarbons are burned in a plentiful supply of oxygen, producing carbon dioxide (CO2) and water (H2O).
• Incomplete combustion takes place when there isn't enough oxygen, resulting in the production of carbon monoxide or carbon soot.

Highlight: The combustion of hydrocarbons is an important concept in understanding their use as fuels.

This page provides essential information for students studying organic chemistry as part of their GCSE Chemistry curriculum, particularly for topics related to hydrocarbons and their properties.