Life & Earth Science

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Life &amp; Earth Science

The excretory system allows for the removal of metabolic waste in the form of urine from the body.

Tissues include : muscle tissue, epithelial tissue, blood vessels

The skeletal system protects the internal organs of the body and allows for movement.

Tissues include : bones, cartilage, tendons, ligaments

Animal and plant cells share many common organelles. However, there are some additional specialized structures found in plant cells, including : chloroplasts, a large vacuole, and the cell wall.

Cell Wall:&nbsp;This is the rigid outermost layer of a plant cell. It makes the cell stiff -providing the cell with mechanical support - and giving it protection. Animal cells do not have cell walls.

Vacuoles:&nbsp;These are large sacs that store toxic wastes as well as useful products such as water. These are mainly found in plants, storing a sugary solution known as cell sap.

All living structures are made of&nbsp;cells, which are made of many different molecules. As in other multicellular organisms, cells in the human body are organized into tissues. A&nbsp;tissue&nbsp;is a group of similar cells that work together to perform a specific function. There are four main tissue types in humans (muscular, epithelial, nervous and connective).

An&nbsp;organ system&nbsp;is a group of organs that work together to perform a specific function (for example, the stomach, small and large intestines are all organs of the digestive system, that work together to digest foodstuff, move nutrients into the blood and get rid of waste). The most complex level of organization, the human&nbsp;organism&nbsp;is composed of many organ systems that work together to perform the functions of an independent individual.

An&nbsp;organ&nbsp;is an identifiable structure of the body composed of two or more tissues types (for example, the stomach contains&nbsp;muscular tissue&nbsp;made of muscle cells, which allows it to change its shape

Animal kingdom The kingdom&nbsp;Animalia&nbsp;is the most evolved and is divided into two large groups - vertebrates and invertebrates. These animals are&nbsp;multi-celled, sexual reproduction and the ability to move.&nbsp;This kingdom is one of the most diverse and comprises mammals, fish, birds, reptiles, amphibians, insects, molluscs and annelids, among others. Plant kingdom Trees, plants and other species of vegetation make up part of the&nbsp;Plantae&nbsp;kingdom - one of the oldest, and characterized by its immobile and multicellular nature. The cells contain cellulose and chlorophyll&nbsp;are essential for life on Earth since they release oxygen through photosynthesis.

Cell specialization/differentiation is where special cells called stem cells change into different kinds of cell.

Multicellular organisms begin as just one single cell—a fertilized egg. Growing from one single cell to trillions of specialized cells that perform different functions is a process that happens with the help of&nbsp;DNA&nbsp;and&nbsp;RNA.&nbsp;

Each type of cell formed will then carry out a specific function.

Climate is determined by a region’s climate system. A climate system has five major components: the&nbsp;atmosphere (air), the&nbsp;hydrosphere ( water), the&nbsp;cryosphere (ice), the geosphere ( land), and the&nbsp;biosphere ( living things).

In tundra climates, summers are short, but plants and animals are plentiful. Temperatures can average as high as 10° Celsius (50° Fahrenheit) in July. Wildflowers dot the landscape, and flocks of migratory birds feed on insects and fish.&nbsp;

Polar Climate The two&nbsp;polar climate&nbsp;types, tundra and ice cap, lie within the Arctic and Antarctic Circles near the North and South Poles.&nbsp; 90o -60o&nbsp;latitude Cool summers, cold year-round Dry

Tropical Climates ( tropical wet; tropical monsoon; and tropical wet and dry) Rainforests are places with a tropical wet climate are also known as rainforests. These equatorial regions have the most&nbsp;predictable&nbsp;weather on Earth, with warm temperatures and regular rainfall. Annual rainfall exceeds 150 centimeters (59 inches), and the temperature varies more during a day than it does over a year.

The digestive system is responsible for breaking down large food molecules into smaller nutrients that the body can use.

Tissues include : epithelial tissue (lines the organs) , muscle tissue, mucus membranes.

The respiratory system allow gases ( oxygen, carbon dioxide) to enter and leave the body.

Tissues include : epithelial tissue, muscle tissue, cartilage, vocal cords.

The nervous system is a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body. It helps the body to react to changes in the internal ( cellular) and external environment. As a result, the nervous system controls our reaction time to stimulus ( sudden change in the environment example, light, sound)

The reaction time is defined as the time taken for the body to respond to a stimulus.

The Nervous System In 9 Minutes

Chloroplast:&nbsp;Chloroplasts contain a green pigment (chlorophyll) that traps sunlight and converts it into sugars (food) by a process called photosynthesis. The sugars are a source of energy for the plants and the animals that eat them.

Cyanobacteria, a type of prokaryote capable of photosynthesis, are considered to be the ancestors of chloroplasts!

Cyanobacteria with chloroplast present in the cells.

Voluntary and Involuntary Actions

Voluntary Actions These are actions that are consciously controlled or coordinated by the brain (cerebrum). The response to a stimuli may maybe different and involves many nerve cells.

Involuntary Actions These are rapid, automatic responses which are consciously controlled by the brain. A given stimulus will always produce the same response. This is called a reflex action. Involuntary actions are controlled by the medulla oblangata of the brain.

Voluntary actions include : walking, running, eating etc.

Involuntary actions include withdrawal of the hand from a hot pot, breathing, blinking etc.

Cytoplasm : Jelly-like substance that makes up the cell consisting of 70% water. Many dissolved substances such as nutrients and gases can be found in the cytoplasm.

Cell membrane : It is the structure that surrounds the cell. The cell membrane allows substances to move in and out of the cell.

Mitochondrion (singular) : The mitochondria (plural) are responsible for producing energy from the food taken into the cell. The mitochondria are known as the "powerhouses" of the cell. The energy released from food in the mitochondria is stored in a special molecule called ATP ( Adenosine triphosphate)

Endoplasmic reticulum (ER) : Maze of membrane that extends from the nucleus. The ER transport proteins made in the cell and allows for fat formation.

Vacuole : Sac that stores water and food in the cell.

A neuron cell, also known as a neuron or nerve cell, is an electrically excitable cell that communicates with other cells via specialized connections called synapses. It is the main component of nervous tissue. All animals except sponges and placozoans have neurons, but other multicellular organisms such as plants do not.

The neuron is the basic unit of the nervous system. It consists of four major regions: a. cell body b. dendrites c. an axon d. synaptic terminals The cell body is the enlarged portion of a neuron containing nucleus, cell membrane, and other organelles (for example, the mitochondria and endoplasmic reticulum). The function of the cell body to receive information from the dendrites and transmit it to the axon. The dendrites and axon are thin cytoplasmic extensions of the neuron. Dendrites carry information received from the sense organs to the cell body. The single long axon carries signals away from the cell body. Once an electrical signal has arrived at the end of an axon, the synaptic knobs release a chemical messenger called a neurotransmitter, which relays the signal across the synapse to the next neuron or to the effector cell.

A sperm cell is specialized in such a way that it has a tail, a large number of mitochondria and a small vacuole containing enzyme. The tail is very important for movement of the sperm.

The large number of mitochondria provides energy for movement. The enzyme in the small vacuole helps the sperm to digest the wall of the egg cell so that the nucleus can enter the egg cell for fertilization to take place.

A red blood cell is a tiny, disc-like cell (biconcave shape) which has no nucleus. Each red blood cell lives for about 4 months, after which it breaks down. Function of red blood cell: To transport oxygen to all respiring cells all over the body.

Red blood cell contains haemoglobin that carries the oxygen in the cell. It has no nucleus so that more space is available to transport oxygen.

The pupil reflex ensures that an appropriate amount of light enters the eye in dim and bright light.

Comparison between voluntary and involuntary actions

The cerebrum of the brain controls voluntary actions, while the medulla oblangata coordinates involuntary actions.

A muscle cell is generally elongated and elastic containing mitochondria in large number. The elongated and elastic feature helps muscle tissues to contract and relax to move the bones.

The large number of mitochondria is very important in tissue respiration in the muscle cells (Remember, energy is required for muscle to contract)

Functions of parts of the leaf

Lamina/leaf blade : broad, flat section of the leaf. It contains a lot of chlorophyll and is responsible for capturing/absorbing sunlight. Gases also diffuse in and out of the lamina. Mid-rib/main vein : large vein running in the middle of the leaf that divides into into two parts. It provides support to the leaf, transport water and mineral salts to and from the leaf.

Petiole/leaf stalk : Long stem-like structure at the base of the leaf. It attaches the leaf to the stem at right angle to capture as much sunlight as possible. Net veins : small veins that extends from the mid-rib. Transport mineral salts and water. The net veins also provide support in keeping the leaf open to sunlight. Stomata : small openings in the lamina that allow gases to move in and out for use in photosynthesis and respiration. Venules : These are smaller veins that extends from the net veins and help in transporting substances in and out of the leaf.

Leaf cell ( Palisade cell)

Palisade cells in the leaf contains a large number of chloroplasts. The chloroplasts allow the cells to make food during photosynthesis.

The palisade cells are positioned close to the upper section of the leaf to capture maximum amount of sunlight.

Nucleus : found towards the center of the animal cell. Controls all the activities that occurs in the cell. Contains the DNA ( deoxyribonucleic acid) which codes for specific traits ( eye color, height..) in organisms.

Ribosomes : smallest organelle in the cell. It is produced by the nucleolus present in the nucleus. The ribosome is responsible for making proteins that will help the cell to grow. They can be found on the endoplasmic reticulum or in the cytoplasm.

Fungi kingdom This kingdom includes yeasts, moulds and all species of mushrooms and toadstools. These&nbsp;multicellular organisms&nbsp;have chitin in their cell walls,&nbsp;feed off other living things,&nbsp;and reproduce through spores. Protista kingdom The&nbsp;Protista&nbsp;kingdom contains the common ancestor but not all its descendants - and&nbsp;it includes those organisms that are not deemed to be animals, plants or fungi&nbsp;such as protozoa.

Monera kingdom This is the kingdom of&nbsp;microscopic living things&nbsp;and groups together the prokaryotes (archaea and bacteria). This group&nbsp;is present in all habitats and is made up of single-cell things with no defined nucleus.

Organelles are special structures found within the cell. Each organelle has a specific job to carry out to help the cell to function properly. An example of an organelle is the nucleus

Our sense organs detect changes in the world around us known as&nbsp;stimuli. The sense organs contain groups of specialized cells called&nbsp;receptor cells&nbsp;which produce electrical impulses in response to specific stimuli.

Mild Climates&nbsp; Regions with mild and continental climates are also called temperate regions. Both climate types have distinct cold seasons. In these parts of the world, climate is influenced mostly by latitude and a region’s position on the continent. Mediterranean Mediterranean climates have warm summers and short, mild, rainy winters. Mediterranean climates are found on the west coasts of continents between 30° and 40° latitude, and along the shores of the Mediterranean Sea.

Areas with continental climates have colder winters, longer-lasting snow, and shorter growing seasons. They are the transition zones between mild and polar climates. Continental climates experience extreme seasonal changes. There are three types of continental climate—warm summer, cool summer, and subarctic. All these climates exist only in the Northern Hemisphere. Usually, continental climates are found in the interior of continents.

Continental climate is at the center of a continent with hot summers and cold winters. 

Differences between weather and climate

Weather is a specific event such as a thunderstorm or a hot day, that happens over a few hours, days or weeks. Climate is the average weather conditions in a place over 30 years or more. NASA has observed that Earth's climate is getting warmer.

What's the difference between weather and climate?

Weather a. day to day information of atmospheric changes at a specific time. b. short-term atmospheric conditions c. changes very frequently Climate a. average weather conditions over 30 years. b. long term average atmospheric conditions c. climate conditions change over a long period

The circulatory system distribute heat, gases and nutrients around the body.

Tissues include : blood, blood vessels, muscle tissue

The nervous system allows the body to detect and respond to changes in the environment example: heat, pressure, low temperature.

Tissues include : spinal cord, nerves, muscle tissue

This is used for holding liquid samples or to observe a chemical reaction.

A filter funnel is used for filtering mixtures or safely transfer liquids between containers.

This is used for holding solid or liquid samples. It can be used during the weighing of a sample.

A test tube is used to hold both solid and liquid samples. It can also be used for heating of samples.

Examples of specialized plant cells

Root hair cells are actually modified epidermal cells of the roots. A root hair cell has a long and narrow protrusion (may also be referred to as hair-like structure). A root hair cell has a large vacuole with lots of mitochondria in the cytoplasm. Function of root hair cell: To absorb water and mineral salts by osmosis and active transport respectively.

ADAPTATIONS TO FUNCTION: The hair-like structure helps the root hair cell to absorb more water and mineral salts from the soil.

Common Laboratory Equipment

This is used for measuring volume of liquid samples.

Beakers are useful as a reaction container or to hold liquid or solid samples. They are also used to catch liquids from titrations and filtrates from filtering operations.

A spatula is used for transferring solid.

An evaporating dish is used to hold samples during heating.

Dry Climates Regions lying within the dry&nbsp;climate group&nbsp;occur where precipitation is low. There are two dry climate types: arid and semiarid. Most arid climates receive 10 to 30 centimeters (four to 12 inches) of rain each year, and semiarid climates receive enough to support extensive grasslands. The temperature in the arid Death Valley National Park, California, U.S., reached 56.7° Celsius (134° Fahrenheit) on July 10, 1913—the highest temperature ever recorded.

Some tropical wet climates are wet throughout the year. Others experience more rainfall during the summer or winter, but they never have especially dry seasons. The U.S. state of Hawaii; Kuala Lumpur, Malaysia; and Belém, Brazil, are examples of areas with tropical wet climates.

The nerve cell sends and receives messages from the body to the brain and then back to the body.

Long structures called axons allow nerve cells to transmit signals to other cells. 

Nerve cells can also receive these signals through rootlike extensions known as dendrites.

Classification of living organisms into Kingdoms

Vocabulary Cells are the basic unit of structure and function in all living organisms. Organisms maybe unicellular or multicellular. Unicellular organisms are made up of only one cell example bacteria, fungi. Multicellular organisms are made up of many cells example: plants, animals, some fungi.

Millions of living things inhabit our planet, but did you know that they are divided into five separate kingdoms? Some, like animals and plants, are visible to the naked eye; but others, like bacteria, can only be seen under a microscope.&nbsp;

Cells - Introduction | Biology | Don't Memorise

Equation of photosynthesis

"Photo" refers to light and "synthesis" means to build up. Photosynthesis is therefore the process where green plants make food using sunlight. Plants need carbon dioxide and water in order to make food in the form of sugar (glucose) and produce oxygen at the same time. Carbon dioxide diffuses into the leaf from the atmosphere and water enters the root from the soil.

carbon dioxide + water -------&gt; glucose + oxygen 6CO2 + 6H2O -------&gt; C6H12O6 + 6 O2

The leaf is the major organ of photosynthesis. Chlorophyll is the green pigment that captures sunlight in the leaf.

THE PHOTOSYNTHESIS SONG

https://www.sciencefacts.net/parts-of-a-leaf.html

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