What are ‘organelles’? subunits in the cytoplasm that carry out a particular function such as the: nucleus mitochondria
Nucleus each cell has one nucleus a cell cannot live for long without a nucleus the nucleus controls the activities of the cell Nucleus in a cheek cell.
The nucleus contains: thread-like structures called: CELL chromosomes chromosomes Chromosome contain DNA (deoxyribonucleic acid) DNA
The nucleolus is a dark region in the nucelus Function of the nucleolus: certain chemicals are made e.g. RNA (ribonucleic acid) which then work in the cytoplasm nucleolus
VacuolesAnimal cells: have small vacuoles that are temporary Amoeba engulfs food. Phagocyte engulfs bacteria.
Plant cells: have a large central, permanent vacuole full of SAPSAP is a mixture of: sugars salts water pigments
Mitochondria are structures in which aerobic respiration occurs are called the ‘power houses’ of the cell as they release energy are usually sausage-shaped
Mitochondriaare seen only by an electron microscope
Explain why there are more mitochondria in muscle cells than in skin cells. Moremitochondria in musclecells as they use more energy.
Structures ONLY in plantsCell wallChloroplasts
The cell wall is: a non-living structure surrounding the cell membrane made of cellulose fully permeable i.e. substances pass freely through it cell membrane cell wall
Functions of the cell wall1. gives rigidity to the cell2. together with the central vacuole, it provides support
Chloroplasts contain the greenpigment: CHLOROPHYLL
Function of chlorophyll traps light for photosynthesis chloroplast
QUESTION: SEP, 2011Give a reason for each of the followingobservations.i) Large permanent vacuoles are present in plant cells. (2) Gives shape and rigidity to the plant cells.
QUESTION: SEP, 2011Give a reason for each of the followingobservations.ii) Animal cells tend to have irregular shapes. (2) Cells are surrounded by a thin cell membrane which is not stiff.
QUESTION: SEP, 2011Give a reason for each of the followingobservations.iii) Sperm cells are haploid. (2)After fertilisation, the diploid number of chromosomes is restored.
CELL SPECIALISATION specialisation is the process by which cells change their shape to carry out a particular task specialisation happens in multicellular organisms
Examples of specialised animal cells: white blood cells change their shape to engulf bacteria nerve cell contains a long fibre to conduct impulses
Examples of specialised animal cells: muscle cell elongated cell which can shorten red blood cell has no nucleus to have more space to carry more oxygen
Examples of specialised plant cells:1. guard cells bean-shaped cells with a pore in between to allow gas exchange2. palisade cells elongated cells with many chloroplasts to carry out photosynthesis
Examples of specialised plant cells:3. epidermal cells transparent to let light pass through them
Unicellular Multicellular organism organismone cell: cells become carries out all the differentiated vital functions into tissues is capable to live on its own
Differentiated means cells become adapted during development to a specific function
Cells in a tissuehave the same structure and functiona tissue cannot live on its own
Examples of animal tissues muscle tissue blood tissue nerve tissue bone tissue
Examples of plant tissuesPhotosynthetic tissue Vascular tissue: xylem & phloem Epidermal tissue: Protects from water loss & pathogens
QUESTION: SEP, 2011Blood is an animal tissue.List TWO plant tissues and give thefunction of each. (6)Epidermal tissue:Photosynthetic tissue:Vascular tissue:
Question: MAY, 2010Write the appropriate plant or animal tissue for eachof the following descriptions. (6) Description Name of tissue Tissue used in the translocation of organic solutes. Tissue conducts nerve impulses. Tissue contracts to support and move the body. Tissue found in leaf containing numerous chloroplasts. Tissue acts as the living protective layer in leaf. Tissue carries substances round the body.
Question: MAY, 2010Write the appropriate plant or animal tissue for eachof the following descriptions. (6) Description Name of tissue Tissue used in the translocation of organic solutes. Phloem Tissue conducts nerve impulses. Nervous Tissue contracts to support and move the body. Muscle Tissue found in leaf containing numerous chloroplasts. Photosynthetic Tissue acts as the living protective layer in leaf. Epidermis Tissue carries substances round the body. Blood
Organism Levels of cellular organisationSystem Organ Tissue Cell
Systems are made up of a group of organs e.g. heart + blood vessels make up the circulatory system
Examples of SystemsSkeletalCirculatoryImmuneRespiratoryDigestiveExcretoryReproductiveNervousEndocrineMuscular
QuestionTo which systems of the body do the followingorgans belong? Chose from the list: circulatory nervous reproductive breathing skeletal excretory digestivea) Gut: digestive b) Bladder: excretoryc) Skull: skeletal d) Heart: circulatorye) Ears: nervous f) Ovaries: reproductiveg) Lungs: breathing h) Spinal cord: nervous
Organism results from many systems working together I am an organism.