1) Cell structure and Organisation

How does Root hair cell adapt to function?

- The root hair cell has a long and narrow root hair. This increases the surface area to volume ratio of the cell. Water and mineral salts can be absorbed at a faster rate.

Chloroplasts

-Oval structures found in plant cells -Contain a green pigment called chlorophyll -Essential for photosynthesis

Name two structures in a cell visible only under an electro microscope and state the function fo each one.

1) Mitochondrion - Aerobic respiration to oxidise glucose and release energy for the cell 2) Ribosome - Site of protein synthesis

Name two structures in a cell visible only under an electron microscope and state the function of each one.

1) Mitochondrion - Aerobic respiration takes place in the mitochondrion. During this process, glucose is oxidised to release energy for the cell 2) Ribosome - Ribosome is the site of protein synthesis

Examples of specialised cells

1) Red blood cell 2) Xylem vessels 3) Root hair cell

How does red blood cell adapt to function?

1) The red blood cell contains haemoglobin (a red pigment). Haemoglobin binds to oxygen and transports it round the body. 2) It has a circular, biconcave shape. This increases the surface area to volume ratio. It can take in and release oxygen at a faster rate 3) Lacks a nucleus. This enables the cell to store more haemoglobin for transport of oxygen Human red blood cells are not rigid. It's elastic and can change its shape to squeeze through blood capillaries

How substances made by the endoplasmic reticulum enter the Golgi apparatus and are finally secreted out of the cell

1) Vesicles transport substances within the cell. Small vesicles containing substances made by the ER are pinched off by the ER 2) These vesicles then fuse with the Golgi apparatus and release their contents into the Golgi apparatus. The substances made by the ER may be chemically modified inside the Golgi apparatus. 3)Secretory vesicles containing these modified substances are pinched off from the Golgi apparatus. They then move to the cell surface membrane. 4) The secretory vesicles fuse with the cell surface membrane and their contents are released outside the cell.

How does xylem vessels adapt to function?

1) Xylem vessels are Long hollow tubes extending from the roots to the leaves 2) They are narrow and have no cross-walls (partition walls) to obstruct water flow through the lumen (a hollow space in the vessel) 3) They have no protoplasm to offer resistance to water flow 4) Their walls are thickened with lignin (a woody substance) to prevent collapse of the vessel

What does the nucleus contain and what are their functions?

1)Nuclear envelope separates the contents of the nucleus from the rest of the cytoplasm 2)Nucleoplasm is the dense material within the nucleus 3)Nucleolus plays a part in the making of proteins in the cell 4)Chromatin • This is a mass of Long thread-like structures found within the nucleus • Each chromatin thread is made up of proteins and a compound called deoxyribonucleic acid or DNA. Hereditary information is stored in the DNA. DNA also carries instructions that a cell needs for carrying out its activities • When the cell dividing, the chromatin threads condense and become highly coiled structures called chromosomes. Under the light miscroscope, the chromosomes appear as thick rod shapes structures

Example of cells which contains a nucleus and cells which does not

A mature root hair cell contains a nucleus. A mature red blood cell, sieve tube element and Xylem vessel do not contain a nucleus because their main function is to transport substances. Without a nucleus, a red blood cell can carry more oxygen while a sieve tube element and Xylem vessel can carry fluids without obstruction.

What is a tissue?

A tissue is a group of cells with similar structures which work together to perform a specific function. There are two types of tissue: 1) Simple tissue 2) Complex tissue

Function of mitochondrion

Aerobic respiration is carried out in the mitochondrion. During this process, glucose is oxidised to release energy for the cell. ( Double membrane )

Organ

An organ contains more than one type of tissue, all working together for a specific function. - For example, the stomach contains gland tissue, muscular tissue and nervous tissue. They all work together for the digestion of food. •The gland tissue secretes enzymes to digest the food • The muscular tissue contracts to churn the food and mixes the food with digestive enzymes • The nervous tissue detects the presence of food in the stomach. It causes the gland tissue to secrete digestive enzymes. - Another example would be the leaf. Lead contains mesophyll tissue, Xylem tissue and phloem tissue. They all work together for plant Nutrition and transport. • The mesophyll tissue carries out photosynthesis • The Xylem tissue transport water and mineral salts to the leaf to enable photosynthesis • The phloem tissue transports products of photosynthesis (food substances) away from the leaf.

organ system

An organ system consists of several organs working together for a common purpose. Some examples of organ systems in humans include the digestive system, circulatory system, respiratory system and transport system. In plants, examples or organ systems include the root system and the shoot system

State the similarities and differences between the structure of plant and animal cells as seen under a light microscope (4m)

Both plant and animal cells contain a nucleus, a partially permeable cell membrane and cytoplasm. A plant cell has a cellulose cell wall that provides support for the cell while an animal cell does not have a cell wall. A plant cell has chloroplasts that enable it to carry out photosynthesis while an animal cell does not have Chloroplasts. A plant cell has a large central vacuole that contains cell sap while an animal cell has many smaller vacuoles.

simple tissue

Cells of the same kind may group together to form a simple tissue - Example of simple tissues in the human body are muscular tissue and epithelial (skin tissue). - Examples of plant tissues are epidermis (the tissues that covers the surface of leaves, stems and roots) and mesophyll tissues in leaves that carry out photosynthesis

Levels of organisation in living things are in the following sequence

Cells> Tissue> Organ> Organ system> Organism

An Animal Cell was unable to undergo cell division. Which of the following structures could have been damaged or missing from the cell?

Chromatin and centrioles

Which cell components are needed to synthesise and build proteins within the cell?

Chromatin threads and Ribosome DNA provides information on the proteins to be synthesise while ribosome is the site of protein synthesis

complex tissue

Complex tissue contains more than one type of cells - For example, blood is a complex tissue . It consists of red blood cells, white blood cel, platelets and plasma - Complex tissues in plants are Xylem and phloem tissues • Xylem consists mainly of vessels and dead cells. • Phloem tissue consists mainly of sieve tubes and companion cells

Using a named plant structure as an example, describe the relationship between cells, tissues and organs (4m)

Leaf is the plant structure where photosynthesis takes place. Cells are the basic units of life. Similar cells which work together to carry out a particular, specific function is called a tissue. For example, palisade mesophyll cells in the leaf form the palisade tissue and spongy mesophyll cells in the leaf form spongy mesophyll tissue. These tissues are simple tissues. Some tissues may contain different types of cells like Xylem tissue and phloem tissue. These tissues are complex tissues. For example, phloem tissue consists of sieve tube cells and companion cells. Different tissues which work together which work together to carry out a particular specific function is called an organ. The palisade tissue, spongy mesophyll tissue, Xylem tissue, phloem tissue and other different tissues form the organ, leaf, which makes food for the plant.

Mitchondria

Mitchondria ( singular: mitochondrion ) are small oval or sausage shaped organelles. Aerobic respiration occurs in the mitchondria. During aerobic respiration, food substances are oxidised to release energy. This energy may be used by the elk to perform cell activities such as growth and reproduction. A mitochondrion has a double membrane.

At which part of the living cell is oxygen concentration lowest?

Mitochondria. Aerobic respiration is carried out in a mitochondrion. The mitochondrion uses a large amount of oxygen to oxidise glucose molecules to release energy for the cell. Thus, it's oxygen concentration is the lowest.

In which part of a living cell is the oxygen concentration lowest?

Mitochondrion. Aerobic respiration is carried out in a mitochondrion. The mitochondrion uses a large amount of oxygen to oxidise glucose molecules to release for the cell. Thus, its oxygen concentration is the lowest.

Which of the following shows the correct order of organelles when protein is synthesised and secreted from a cell?

Nucleus->Ribosome->Golgi body->Vesicles

Differences between plant and animal cells ( points )

Plant cell | Animal cell - cell wall present | Cell wall absent - chloroplast present | absent - Centrioles absent | Centrioles present - A large central | Vacuoles are small and Vacuole | many

Structure and function of Rough endoplasmic Reticulum

Rough endoplasmic reticulum (RER) consists of a network of flattened spaces lined with a membrane. (Structure): - Its surface appears rough when viewed under the electron microscope. This is because small particles called ribosomes are attached to its outer surface - The outer surface of the RER is continuous withe the nuclear envelope (Function): - The RER transports proteins made by ribosomes to the Golgi apparatus for secretion out of cell

Structure and functions of Ribosomes

Small round structures. They are either attached to the membrane of the endoplasmic (ER) or lie freely in the cytoplasm (Function): They are needed to synthesise proteins in the cell. - The ribosome attached to the ER make proteins that are usually transported out of the cell - The ribosomes lying freely in the cytoplasm make proteins that are used within the cytoplasm of that cell

Centrioles

Small,hollow cylinders A pair of centrioles are usually found close to the nucleus Cell organelle that aids in cell division in animal cells only

Structure and function of Smooth endoplasmic reticulum

Smooth endoplasmic reticulum (SER) does not have ribosomes attaches to its membrane. SER is more tubular than RER. (Function): - synthesis substances such as fats and steroids. Sex hormones in mammals are steroids. - convert harmful substances into harmless materials. This process is called detoxification.

Structure and function of Golgi apparatus

The Golgi apparatus or Golgi body is shaped like a disc. It consists of a stack of flattened spaces surrounded by membranes. Vesicles( tiny spherical spaces enclosed by a membrane) can be seen fusing with one side of the Golgi apparatus and pinching off from the opposite side. (Function): - Chemically modifies substances made by the ER, and - Stores and packages these substances in vesicles for secretion out of the cell.

What is differentiation?

The process by which a cell becomes specialised for a specific function

Vacuoles

Vacuoles are fluid-filed sacs that store substances such as water, food, wastes, salts, or pigment. They are found in both animal and plant cells, but much larger in plant cells. - (Animal) cells have many small vacuoles in That contain water and food substances. These vacuoles usually exists temporarily - (Plant) cells have a large central vacuole which contains a liquid called cell sap. Cell sap contains dissolved substances such as sugars, mineral salts and amino acids. This large vacuoles is enclosed by a partially permeable membrane called the tonoplast (vacuole membrane)

Organism

Various systems together make up the entire body of an organism

Parts of the cytoplasm and their functions

What are the parts of the cytoplasm? - the cytoplasm contains tiny structures called (organelles). Each organelle is specialised for a particular function. Example of organelles are Rough endoplasmic reticulum, Smooth endoplasmic reticulum, Ribosomes, Goligi apparatus( or Golgi body ),mitochondria and chloroplasts.

Functions of main parts of Cells

[Cytoplasm] - Part of the protoplasm between the cell surface membrane and the nucleus. It is where the most cell activities occur. The cytoplam conatin specialized structures called organelles [Nucleus] - The nucleus consists of a small round mass of denser protoplasm called nucleoplasm, surrounded by a membrane called the nuclear envelope -(FUNCTIONS)of the nucleus : •It controls cell acitivites such a cell growth and the repair of worn out parts. •It is essential for cell division. Cells without a nucleus, like the red blood cells of a mammal, are unable to divide. The nucleus contains one or more nucleoli and chromatin [Cell surface membrane] - surrounds the cytoplasm of the cell. The cell surface membrane is made up of lipids and proteins. It is a partially permeable membrane. This means that it only allows some substances to pass through it. Hence.,(FUNCTION)The cell surface membrane controls substances entering or leaving the cell [Cell wall] - A plant cell also has a cell wall that enclosed the entire the entire plant cell, surrounding the cell surface membrane. The cell wall is made up of cellulose. (FUNCTION)It protects the cell from injury and gives the plant cell a fixed shape. The cell wall is fully permeable. The cell wall is absent in animal cells.