1b Variety of Living Organisms #cricksbiology #GCSE

Summary

This educational video script delves into the classification of living organisms, highlighting the eight characteristics of life and the five kingdoms: plants, animals, fungi, productists, and prokaryotes. It explores each kingdom's unique features, such as chloroplasts in plants for photosynthesis and the absence of cell walls in animal cells, which allows for movement. Fungi are noted for their saprotrophic feeding, while productists are a diverse group including algae. Prokaryotes, like bacteria, are simple single-celled organisms with no nucleus. The script also touches on viruses, which are not considered living, and pathogens causing diseases across different kingdoms.

Takeaways

• 🌿 There are over 10 million species of organisms on Earth, which are categorized into kingdoms based on shared characteristics.
• 🔬 The five major kingdoms of life are Plantae (plants), Animalia (animals), Fungi, Protista, and Prokaryotes (bacteria).
• 🍃 Plants are multicellular with chloroplasts for photosynthesis and have cell walls made of cellulose.
• 🐘 Animals are multicellular and heterotrophic, lacking chloroplasts and cell walls, with movement facilitated by a nervous system.
• 🍄 Fungi are either unicellular or multicellular and obtain nutrients by secreting digestive enzymes externally, with cell walls made of chitin.
• 🌊 Protista is a diverse group of organisms that don't fit into other kingdoms, including both unicellular and multicellular forms like algae.
• 🦠 Prokaryotes are single-celled organisms without a nucleus, having DNA floating in the cytoplasm, and are important decomposers.
• 🧬 Viruses are not considered living organisms as they cannot reproduce independently and require a host cell to replicate.
• 🔬 Eukaryotic cells have a nucleus and membrane-bound organelles, unlike prokaryotic cells which lack these structures.
• 🦠 Pathogens, including fungi, bacteria, protists, and viruses, cause diseases in plants, animals, and humans.
• 📚 Key terms such as 'chloroplasts', 'cell wall', 'saprorophic feeding', and 'eukaryotic' are essential for understanding and should be well understood for exams.

Q & A

What are the eight characteristics of life?

The eight characteristics of life are movement, respiration, sensitivity, homeostasis, reproduction, excretion, nutrition, and growth.

How are living organisms classified into groups?

Living organisms are classified into groups based on their similar characteristics, which are organized into a hierarchical structure starting from kingdoms down to individual species.

What are the five kingdoms of living organisms?

The five kingdoms of living organisms are plants, animals, fungi, productists (or protists), and prokaryotes (which contain bacteria).

What is the main distinguishing feature of plants?

The main distinguishing feature of plants is that their cells contain chloroplasts with the green pigment chlorophyll, enabling them to carry out photosynthesis.

How do animals differ from plants in terms of cell structure?

Animal cells do not contain chloroplasts and they do not have cell walls, allowing them to change shape and move from place to place.

What is unique about fungal cell walls compared to plant cell walls?

Fungal cell walls are not made of cellulose like plant cell walls; instead, they are composed of a substance called chitin.

How do productists differ from plants and animals?

Productists are a mixed group of organisms that do not fit neatly into the plant, animal, or fungi categories. They are mostly microscopic, single-celled organisms with some features resembling plants or animals.

What is the main difference between eukaryotic and prokaryotic cells?

Eukaryotic cells have a nucleus and other membrane-bound organelles, while prokaryotic cells lack a nucleus, mitochondria, and chloroplasts, having their genetic material floating freely in the cytoplasm.

Why are viruses not considered living organisms?

Viruses are not considered living organisms because they cannot reproduce or carry out life processes outside of a host cell and do not exhibit all the characteristics of living things.

What is the role of bacteria in the ecosystem?

Bacteria play a crucial role as decomposers, recycling dead organisms and waste products in the soil, and some are also used by humans to make foods, while others can cause diseases.

What are pathogens and which kingdoms contain them?

Pathogens are organisms that cause disease. The main kingdoms that contain pathogens are fungi, bacteria, productists, and viruses.

Outlines

00:00

🌿 Classification of Living Organisms

This paragraph introduces the concept of classifying living organisms based on shared characteristics. It covers the eight characteristics of life (MRSCHWENGR) and explains how organisms are grouped into kingdoms based on their evolutionary relationships. The five kingdoms identified are plants, animals, fungi, protists, and prokaryotes. The paragraph further delves into the plant kingdom, describing their multicellular nature, the presence of chloroplasts for photosynthesis, and the storage of glucose as starch or sucrose. It also mentions the structural differences between plant cells and other organisms, such as the presence of a cell wall made of cellulose.

05:01

🐇 Kingdoms of Life: Animals and Fungi

The second paragraph focuses on the animal kingdom, highlighting the diversity of animals and their classification into vertebrates and invertebrates. It discusses the absence of chloroplasts in animal cells and their reliance on movement and a nervous system for survival. The paragraph then explores the fungal kingdom, describing fungi as either unicellular or multicellular organisms that obtain nutrients through saprotrophic feeding. It contrasts the composition of fungal cell walls, made of chitin, with those of plants. Additionally, it touches upon the reproductive structures of fungi, such as mushrooms and toadstools, and their role in forming mycelium networks.

10:03

🦠 Prokaryotes, Viruses, and Pathogens

The final paragraph discusses the prokaryotic kingdom, emphasizing the structural simplicity of prokaryotic cells, which lack a nucleus and organelles. It differentiates between eukaryotic and prokaryotic cells and provides examples of bacteria, including their shapes and functions. The paragraph also introduces viruses as non-living entities that require host cells to reproduce, explaining their simple structure consisting of genetic material enclosed in a protein coat. It concludes by defining pathogens as disease-causing organisms, mentioning examples from various kingdoms and the importance of understanding key terminology related to these concepts.

Keywords

💡Characteristics of Life

The characteristics of life refer to the defining traits that distinguish living organisms from non-living entities. In the video, these are remembered by the acronym 'MRSCHWENG,' which stands for Movement, Respiration, Sensitivity, Homeostasis, Reproduction, Excretion, Nutrition, and Growth. These characteristics are essential for understanding what it means to be alive and are used to identify whether something is a living organism.

💡Kingdom

A kingdom is the highest taxonomic rank in the classification of living organisms. The video mentions five kingdoms: Plantae (plants), Animalia (animals), Fungi, Protista, and Prokaryotes (which include bacteria). Each kingdom is a group of organisms that share certain characteristics and are believed to have evolved from a common ancestor.

💡Evolution

Evolution is the process by which species of organisms change over time through genetic variation and natural selection. The video suggests that members of each kingdom share common ancestry, which is reflected in their structural and functional similarities. This concept is fundamental to understanding the diversity of life on Earth and how it has developed over time.

💡Chloroplasts

Chloroplasts are organelles found in plant cells that contain the green pigment chlorophyll. They are essential for photosynthesis, as described in the video, where light energy is used to convert water and carbon dioxide into glucose and oxygen. Chloroplasts are a key feature that distinguishes plants from other kingdoms and are central to their ability to produce their own food.

💡Cell Wall

A cell wall is a rigid layer surrounding some plant, fungal, and prokaryotic cells, providing structural support and protection. In the video, it is mentioned that plant cells have cell walls made of cellulose, which is different from the chitin that makes up fungal cell walls. The cell wall is a critical component in the structure and function of these organisms.

💡Vertebrates and Invertebrates

Vertebrates are animals with a backbone or spinal column, while invertebrates lack one. The video uses this distinction to categorize animals within the Animalia kingdom. Examples of vertebrates include humans, horses, and dogs, whereas insects, worms, and starfish are invertebrates. This classification is important for understanding the diversity within the animal kingdom.

💡Saprotrophic Feeding

Saprotrophic feeding is a mode of nutrition where organisms, like fungi, secrete digestive enzymes externally to break down food into smaller molecules that can then be absorbed. The video explains that fungi do not photosynthesize and instead obtain their nutrients by breaking down dead organic matter. This feeding mechanism is a key characteristic of fungi and is essential for their survival.

💡Chitin

Chitin is a polysaccharide and a major component of the cell walls of fungi and the exoskeletons of arthropods. In the video, it is mentioned that fungal cell walls are made of chitin, unlike the cellulose found in plant cell walls. Chitin provides structural support and is a key component in the biology of fungi.

💡Prokaryotes

Prokaryotes are single-celled organisms that lack a nucleus and other membrane-bound organelles. The video explains that prokaryotes, such as bacteria, are simpler and smaller than eukaryotic cells. They are important for various biological processes, including decomposition and disease. The distinction between prokaryotes and eukaryotes is fundamental to understanding cellular biology.

💡Viruses

Viruses are infectious agents that are not considered living organisms because they cannot reproduce on their own and require a host cell to replicate. The video discusses how viruses, such as HIV and the influenza virus, infect host cells and use the host's machinery to produce more virus particles. Viruses are a significant topic in biology due to their role in disease and their unique position between living and non-living entities.

💡Pathogens

Pathogens are disease-causing organisms, which can be found across several kingdoms, including fungi, bacteria, protists, and viruses. The video mentions examples like athlete's foot fungus, salmonella bacteria, and the HIV virus. Understanding pathogens is crucial for studying infectious diseases and developing treatments and preventive measures.

Highlights

Lesson focuses on classifying living organisms by similar characteristics.

Recap of the eight characteristics of life remembered as MR SCHWENG.

Introduction to the concept of species and the vast number on Earth.

Explanation of the hierarchical classification system for organisms.

Description of the five kingdoms: plants, animals, fungi, productists, and prokaryotes.

Plant kingdom includes trees, flowering plants, mosses, and ferns.

Plants are multicellular with chloroplasts for photosynthesis.

Animal kingdom comprises vertebrates and invertebrates.

Animal cells lack chloroplasts and have the ability to change shape.

Fungi kingdom includes mushrooms, toadstools, molds, and yeasts.

Fungi cells have cell walls made of chitin and engage in saprotrophic feeding.

Productista kingdom is a mixed group of organisms not fitting into other categories.

Prokaryotes are organisms with simpler cells lacking a nucleus.

Bacteria are prokaryotic, single-celled organisms with various shapes.

Bacterial cell walls are made of peptidoglycan and some have a capsule for protection.

Viruses are not considered living things and are obligate parasites.

Viruses are composed of genetic material surrounded by a protein coat.

Pathogens are organisms that cause disease, including fungi, bacteria, productists, and viruses.

Importance of learning buzzwords and technical terms for exams.

Transcripts

[Music]

this lesson

we are going to be looking at the

variety of living organisms and how they

can be grouped together by similar

characteristics

just to recap you should now know the

eight characteristics of life

remembered as mr schweng movement

respiration sensitivity homeostasis

reproduction excretion nutrition

and growth now we know how to identify

whether something is living or not

let's look at the different types of

living organisms

there are more than 10 million species

of organisms living on earth

and then there are many species which

have sadly become extinct

to try to put some order into these

species they've been placed into groups

called

kingdoms then each kingdom is broken

down into smaller groups

which then broken down into smaller

groups and so on until we get to the

individual species

members of each group are related they

are descended from a common ancestor

by the process of evolution which we

cover later on in the course

the common ancestry is reflected in the

similarities of structure and function

of the members of a group

the five kingdoms are plants animals

fungi productists and prokaryotes

which contain bacteria

let's look at the plants to start with

this kingdom contain a familiar plant

such as trees

flowering plants such as cereal like the

maize shown here

legumes such as peas or beans and one of

my favorite

strawberry plants but also contain the

simpler plants such as mosses and ferns

all plants are multicellular which means

they are made

up of many cells their main

distinguishing feature

is that their cells contain chloroplasts

which contain the green pigment

chlorophyll

and they carry out photosynthesis this

is the process that uses light

energy to convert water and carbon

dioxide into glucose and oxygen

this glucose can be made into starch

which can then be stored in their cells

until it is needed or it can be

converted to sucrose

to be transported around the plant to

where it is needed

plant cells have a cell wall around the

outside of them

and this cell wall is made up of a

carbohydrate called

cellulose

next we will look at the animals we

belong to the animal kingdom

there is a huge variety of animals

including the well-known ones such as

horses dogs

and insects like this house fly and the

mosquito here

and fish but also sponges mollusks worms

starfish and crustaceans

animals can be split into vertebrates

like us which means they have a vertical

column or backbone

and introvert invertebrates such as

insects which do not have a backbone

animals are also multicellular organisms

their cells do not contain chloroplasts

as they eat their food

they do not need to make it by

photosynthesis

animal cells also do not have cell walls

so their cells can change shape this is

an important feature for organisms that

need to move from place to place

movement in animals is achieved in

various ways

but often involves coordination by a

nervous system

animals store spare glucose in their

cells as a large compound

called glycogen

the kingdom fungi includes mushrooms and

toadstools

as well as molds like the mucoil shown

here

which you may have seen growing on

vegetables which have been forgotten in

the vegetable rack

these groups of fungi are multicellular

but some fungi such as the yeast shown

here

are unicellular in other words made of

single cells

the cells of fungi do not contain

chloroplasts

as they do not photosynthesize fungi get

their food by secreting digestive

enzymes

onto the food and once it is digested

into smaller molecules

the fungicide absorbs it this is known

as

saprotrophic feeding because the

digestive enzymes are secreted

out of the cells they are known as extra

out of

cellular out-of-the-cell enzymes

like plant cells fungal cells have cell

walls but they are not made of cellulose

like implants

instead they are made of substance

called chitin

the cells can also store carbohydrate

and they use

glycogen for this like animal cells the

mushrooms and toadstools you see grey in

the fields

are actually the reproductive organ

called a fruiting body

once they have stopped reproducing these

fruiting bodies die back

but this leaves the main part of the

fungus under the soil

which are the thread-like filaments

called hyphae

you sometimes see these as fairy rings

in fields

here the hyphae are radiating out from

the center of the circle

and when the fungus is ready to

reproduce the fruiting

bodies grow to form the perimeter of the

circle

these hyphae form a complex mesh-like

network

called a mycelium the hyphy cells

contain more than one nucleus per cell

the kingdom productista or product tests

are sometimes called the dustbin group

but please don't call them this

in an exam because they are mixed group

of organisms that don't fit

into the plants animals or fungi groups

most productives are microscopic

single-celled organisms

some look like animal cells such as

amoeba

and some have features of like plants

such as this chlorella

algae belong to productista most algae

are unicellular

but some species such as seaweeds are

multicellular

and can grow to a great size seaweeds

however is just a general term for the

plant-like structures growing in the sea

seaweeds can actually be plants

productista or

even prokaryotes the productist

plasmodium

shown here is responsible for causing

malaria

there are two main distinct types of

cells

eukaryotes and prokaryotes

all the organisms described so far are

composed of eukaryotic cells

which means they have a nucleus these

eukaryotic organisms have a nucleus

surrounded by a membrane

along with other membrane-bound

organelles such as

mitochondria and chloroplasts but there

are also

organisms made of simpler cells which

have no nucleus

mitochondria or chloroplasts the genetic

material is just

floating freely in the cytoplasm these

are called prokaryotic cells

prokaryotic means before a true nucleus

the kingdom prokaryotes contain bacteria

which are microscopic single-celled

organisms

their cells are much smaller about 10

times smaller to give a rough idea

than those of eukaryotic organisms and

have a much simpler structure

there are three basic shapes of bacteria

spheres rods and spirals

but they all have a similar internal

structure

bacterial cells are surrounded by a wall

for protection

and to maintain the shape

bacterial cell walls are made of

peptidoglycan which is a mixture of

carbohydrates and proteins

some species have another layer outside

this wall called a capsule or slime

layer

both give the bacterium extra protection

the cell has no nucleus instead its dna

is in a single circular chromosome

floating in the cytoplasm

they also have plasmids which has small

circular rings of dna

carrying some of the bacterium's genes

about 75 percent of bacteria contain

plasmids

some but not all bacteria use long

whip-like structure called flagella to

swim

some also contain chlorophyll to carry

out photosynthesis however most bacteria

feed off

other living or dead organisms along

with fungi money bacteria are important

decomposers

recycling dead organisms and waste

products in the soil

some bacteria are used by humans to make

foods such as the production of yogurt

by using lactobacillus bulgaricus

others cause disease such as

pneumococcus

which causes pneumonia

viruses are interesting as they are not

regarded as living things

they are all parasites infecting living

organisms

and can only reproduce inside living

organisms

the cell in which the virus lives is

called the host

there are many different types of virus

some infect the cells of animals

such as a human immunodeficiency virus

which invades human immune cells

thus making the person vulnerable to

other diseases such as pneumonia

and rare cancers and this is regarded as

causing aids other

others infect plant cells such as the

tobacco mosaic virus

which interferes with the ability of the

tobacco plant to make chloroplasts

using causing mottled patches to develop

on the leaves

there are even viruses like the

bacteriophage shown here

which infect bacteria viruses are much

smaller than bacterial cells

roughly 10 to 100 times smaller in

diameter

viruses are not made of cells a virus

particle is very simple

it has no nucleus or cytoplasm as in as

and is composed of a core of genetic

material

surrounded by a protein coat or capsid

the genetic material can be either dna

or rna

in either case a genetic material makes

up just a few genes

all that is needed for the virus to

reproduce inside its host cell

sometimes a membrane called an envelope

may surround a virus particle

but the virus does not make this it is

made by the host cell as it reproduces

the viral particles that have infected

it so why do we say viruses are not

living

viruses do not carry out all of the

normal characteristics of living that

are living things they do reproduce but

they do this by making the host cell

produce the viral particles

so if they are not living they can be

thought of as on the border between an

organism

and a non-living chemical as mentioned

before

viruses reproduce by infecting the host

cell and taking over the host nucleus

to make more virus particles after many

virus particles have been made

the host cell dies and the particles are

released to infect more cells

to finish off we need to look at

pathogens

but what are pathogens they are

organisms that cause disease

the main kingdoms that contain pathogens

are fungi

for example athlete's foot you may be

prone to this if you do not wear socks

in your trainers

as the fungus that causes athlete's foot

likes warm damp

dark areas to grow like in sweaty

trainers

bacteria such as salmonella which causes

food poisoning

product tests like the one we previously

mentioned

which is transmitted by mosquitoes the

plasmodium the organism

causes malaria and then of course there

are the non-living viruses

such as hiv that causes aids the tobacco

mosaic virus infecting funny enough

tobacco plants

influenza and the sarskof2 that causes

covid all of these were mentioned

earlier

of course as always don't forget your

buzzwords

there are some really important words in

here which you may not have come across

before

and you need to be able to spell them

and feel comfortable using them

in your exam answers