bio revision

What characteristics do all living organisms share?

They carry out the eight life processes: movement, respiration, sensitivity, control, growth, reproduction, excretion and nutrition.

Into which five groups can organisms be classified according to shared features?

Plants, animals, fungi, protoctists and prokaryotes.

Which four groups of organisms are eukaryotic?

Plants, animals, fungi and protoctists.

What are eukaryotic organisms also known as?

Eukaryotes.

Can eukaryotic organisms be multicellular or single-celled?

Yes. Eukaryotes can be multicellular or single-celled.

What is the common cellular feature of all eukaryotes?

Their cells contain a nucleus surrounded by a distinct membrane.

Why are animal and plant cells both classified as eukaryotic?

Both contain a distinct membrane-bound nucleus.

What are prokaryotic organisms also known as?

Prokaryotes.

How do prokaryotes differ from eukaryotes in cell number?

Prokaryotes are always single-celled, whereas eukaryotes can be multicellular or single-celled.

Do prokaryotic cells contain a nucleus?

No. Prokaryotic cells do not contain a nucleus.

Where is the genetic material of a prokaryotic cell found?

In the cytoplasm.

What is the form of the genetic material in prokaryotic cells?

A single, circular chromosome of DNA.

How does the size of prokaryotic cells compare with eukaryotic cells?

Prokaryotic cells are substantially smaller than eukaryotic cells.

Which organisms are prokaryotic?

Bacteria.

What are the main features of animals?

They are multicellular; have cells with a membrane-bound nucleus; lack cellulose cell walls and chloroplasts; feed on organic substances made by other living things; often store carbohydrates as glycogen; usually have nervous coordination; and can move from place to place.

Are animals multicellular or single-celled according to the notes?

Multicellular.

Do animal cells contain a nucleus surrounded by a distinct membrane?

Yes.

Do animal cells have cellulose cell walls?

No.

Do animal cells contain chloroplasts?

No.

Why are animals unable to carry out photosynthesis?

Their cells do not contain chloroplasts.

How do animals obtain food?

They feed on organic substances made by other living things.

Which carbohydrate do animals often store?

Glycogen.

What type of coordination do animals usually have?

Nervous coordination.

Can animals move from place to place?

Yes.

What structures are labelled in the typical animal cell diagram described in the notes?

Cell membrane, nucleus, mitochondria, ribosomes and cytoplasm.

What are the main features of plants?

They are multicellular; have cells with a membrane-bound nucleus; have cellulose cell walls and chloroplasts; feed by photosynthesis; store carbohydrates as starch or sucrose; and do not have nervous coordination.

Are plants multicellular or single-celled according to the notes?

Multicellular.

Do plant cells contain a nucleus surrounded by a distinct membrane?

Yes.

What substance makes up plant cell walls?

Cellulose.

Do plant cells contain chloroplasts?

Yes.

How do plants obtain food?

They make food through photosynthesis.

Which carbohydrates can plants store?

Starch or sucrose.

Do plants have nervous coordination?

No.

What structures are labelled in the typical plant cell diagram described in the notes?

Cell wall, cell membrane, chloroplast, nucleus, mitochondrion, ribosomes, cytoplasm and vacuole.

What should you be able to do when comparing groups of organisms in an exam?

Recall their common characteristic features and identify their similarities and differences, including completing comparison tables.

What are the main features of fungi?

They are usually multicellular, although some are single-celled; multicellular fungi consist mainly of hyphae arranged into a mycelium; their cells have a membrane-bound nucleus and chitin cell walls; they lack chloroplasts; they feed by extracellular digestion and absorption; some are parasitic; some store glycogen; and they lack nervous coordination.

Are fungi always multicellular?

No. They are usually multicellular, but some are single-celled.

What is an example of a multicellular fungus given in the notes?

Mucor.

What is an example of a single-celled fungus given in the notes?

Yeast.

What are hyphae?

Thread-like structures that mainly make up multicellular fungi.

What do hyphae contain?

Many nuclei.

What is a mycelium?

A network of hyphae.

What is the arrangement of hyphae in a multicellular fungus?

They are organised into a network called a mycelium.

Do fungal cells contain a nucleus surrounded by a distinct membrane?

Yes.

What substance makes up fungal cell walls?

Chitin.

What are fungal cell walls sometimes described as?

Chitinous cell walls.

Do fungal cells contain chloroplasts?

No.

Why can fungi not carry out photosynthesis?

Their cells do not contain chloroplasts.

How do fungi feed by saprotrophic nutrition?

They secrete extracellular digestive enzymes onto food, digest it outside the mycelium and absorb the digested molecules.

Where are the digestive enzymes secreted by fungi during saprotrophic nutrition?

Outside the mycelium, onto the food.

What is the usual food source for fungi using saprotrophic nutrition?

Decaying organic matter.

What is saprotrophic nutrition?

A method of feeding in which an organism secretes digestive enzymes onto food outside its body or structures and absorbs the digested molecules.

How do some fungi obtain nutrients parasitically?

They feed on living material.

Which carbohydrate can some fungi store?

Glycogen.

Do fungi have nervous coordination?

No.

What examples of fungi are listed in the notes?

Moulds, mushrooms and yeasts.

What structures are labelled in the typical fungal cell diagram described in the notes?

Nucleus, mitochondrion, cytoplasm, ribosomes, cell membrane and chitin-containing cell wall.

What should you practise drawing and labelling for fungi and protoctists?

Fungal cells and protoctist cells.

What are the main features of protoctists?

They are a diverse group, mainly microscopic and single-celled, although some aggregate into colonies or chains of cells forming filaments. Their cells have a membrane-bound nucleus. Some resemble animal cells, while others have plant-like cell walls and chloroplasts. Some photosynthesise, while others feed on organic substances made by other living things. They lack nervous coordination.

How are protoctists described as a group?

They are very diverse and have features different from those of animals, plants and fungi.

Are protoctists mainly microscopic or macroscopic?

They are mainly microscopic.

Are protoctists mainly single-celled or multicellular?

They are mainly single-celled.

What does it mean when protoctists aggregate?

They group together into larger forms.

What larger forms can some protoctists aggregate into?

Colonies or chains of cells that form filaments.

Do protoctist cells contain a nucleus surrounded by a distinct membrane?

Yes.

Which protoctist resembles animal cells and causes malaria?

Plasmodium.

Which disease is caused by Plasmodium?

Malaria.

Which protoctists have plant-like features such as cell walls and chloroplasts?

Some protoctists, including green algae such as Chlorella.

What is Chlorella?

A green alga and an example of a protoctist with plant-like features.

Do all protoctists photosynthesise?

No. Some photosynthesise, while others feed on organic substances made by other living things.

Do protoctists have nervous coordination?

No.

Which protoctists are listed as examples in the notes?

Amoeba, Paramecium, Plasmodium and Chlorella.

What structures are labelled in the protoctist cell diagram described in the notes?

Nucleus, mitochondria, cell membrane, cytoplasm, ribosomes, food vacuoles and contractile vacuoles.

What should you practise doing with images of cells?

Recognising, drawing and interpreting them, including drawing and labelling fungal and protoctist cells.

What does MRS C GREN stand for?

Movement, respiration, sensitivity, control, growth, reproduction, excretion and nutrition.

How many life processes are represented by MRS C GREN?

Eight.

What must an organism do to be considered living according to the notes?

It must carry out all eight life processes.

What does it mean if something does not carry out all eight life processes?

According to the notes, it is either dead or non-living.

What example of a non-living particle or agent is given in the notes?

A virus.

What is nutrition?

The process by which organisms obtain food to provide energy and the materials required for growth and development.

Why do organisms require energy from nutrition?

Energy is necessary to carry out life processes such as movement and excretion.

Which substances do plants use in photosynthesis to produce food?

Sunlight, carbon dioxide and water.

What does photosynthesis produce according to the notes?

Glucose and oxygen.

What is the role of sunlight in plant nutrition?

It provides the energy used in photosynthesis.

How do animals obtain food?

They consume other living organisms to obtain energy and nutrients.

Why do animals consume other organisms?

To obtain energy and the nutrients required to live, grow and develop.

What is digestion?

The breakdown of larger, complex molecules into simpler molecules.

What happens to the simpler molecules produced by digestion in animals?

They are absorbed into the bloodstream and transported to cells.

How are absorbed nutrients used by cells?

They are used in processes such as respiration for energy, and for growth and repair.

How do plants and animals differ in obtaining nutrients?

Plants make their own food by photosynthesis, whereas animals obtain nutrients by eating plants and other animals.

What is the difference between organisms that make their own food and organisms that consume food?

Some organisms, such as plants, make their own food, while others, such as animals and fungi, take in food to obtain nutrients.

What is respiration?

A chemical process carried out in all living organisms.

What happens to glucose during respiration?

Energy is released from glucose.

What is aerobic respiration?

Respiration in which energy is released from glucose in the presence of oxygen.

What is anaerobic respiration?

Respiration in which energy is released from glucose in the absence of oxygen.

What waste products do the notes associate with respiration reactions?

Carbon dioxide and water.

In what form is energy transferred during respiration?

ATP.

What does ATP represent in the notes?

The form in which energy is transferred during respiration.

What is gas exchange?

The process of getting oxygen into cells and carbon dioxide out.

How does gas exchange differ from respiration?

Gas exchange moves oxygen into cells and carbon dioxide out, whereas respiration uses oxygen supplied through gas exchange to release energy in the form of ATP.