Unit 1 - Cells

What is the basic unit of life?

What is the basic unit of life?

Cells

What are cells made up of?

Organelles

What are organelles?(2)

Organelles are sub-units which make up a cell with a particular structure & function

What are oragnelles made up of?

Molecules

What are molecules made up of?

Atoms

What can one use to visualise cellular structures or the like?

A light microscope

What are the main features & functions of the cell surface membrane?(3)

It is a thin layer surrounding the cell which prevents cells content from escaping, acting as a boundary layer which separates the cells contents from its surroundings. It also controls the exit and entry of dissolved substances. (water, sugar & oxygen are allowed to enter whilst carbon dioxide and waste substances are allowed to exit)

What are the main features & functions of the cytoplasm?(4)

It is a jelly-like substance which is made up of 90% water. A no. of organelles, proteins & lipids are suspended in it and it is a site where many chemical reactions take place.

What are the main features & functions of the mitochondrion?(3)

"It's a small, membrane-bound organelle whose function is to carry out respiration to release energy from the glucose present in the cell"

What are the main features & functions of the ribosome?

It's the site where protein synthesis takes place

What are the main features & functions of the nucleus?(3)

It contains the genetic material (DNA which makes genes on chromosomes) which carries the coded instructions for controlling the activities and characteristics of the cell. It is the control centre for chemical reactions taking place in the cytoplasm of the cell.

What are the main features & functions of the chloroplast?(5)

"It's a membrane-bound organelle with green colour due to the green pigment chlorophyll. It carries out photosynthesis with the help of chlorophyll, water, sunlight, carbon dioxide & a good temp. Photosynthesis is important because it is the way a plant obtains its food."

What are the main functions & features of the cellulose cell wall?(5)

"It is the outermost layer of the cell made up of cellulose (dead layer of cells) and it's function is to give shape & support the plant cell. It is a dead structure thus it cannot control what enters or what leaves the cell."

What are the main functions & features of the permanent cell vacuole?(3)

It contains cell sap which is a solution of sugar & salts. It pushes the cell surface membrane against the cell wall keeping the cell turgid.

Which organelles are found in both animal & plant cells?(5)

Cell membrane, cytoplasm, mitochondrion, ribosome & the nucleus

Why are animal and plant cells different?(2)

Animals feed on ready-made food whilst plants make their own through photosynthesis. The fact that animals and plants feed differently from each other explains why their cells are different.

Mention 5 differences in a plant cell when compared to an animal cell.

It has a rectangular shape, a cell wall is present, chloroplasts are present, it has a large permanent vacuole and starch granules are used as a food storage.

Mention 5 differences in an animal cell when compared to a plant cell.

It has a circular shape, no cell wall, no chloroplasts, no vacuole (only small temporary ones) and glycogen granules are used as food storage

What is a unicellular organism?

"It's an organism composed solely of 1 cell which is able to conduct all the processes necessary to keep the cell alive."

What is a Multicellular organism?

"It's a complex organism, such as an animal or a plant which comprises of a large no. of cells."

What is the smallest sub-unit of cellular organisation?

Organelle

Mention 3 membrane-bound organelles.

Nucleus, mitochondria & chloroplasts

"Mention 4 organelles which aren't membrane-bound organelles"

Cellulose cell wall, cell surface membrane, cytoplasm & ribosomes

What is a tissue?

"It's cells of similiar structures & functions massed together"

What are 4 tissues one may find in animals?

Muscle tissue, nervous tissue, epithelial tissue & skeletal tissue

What is the function of muscle tissue?

It contracts to support & move the body

What is the function of nervous tissue?

It conducts & co-ordinates messages around the body

What is the function of epithelial tissue?

It lines tubes (intestines) & forms the skin

Whta is the function of skeletal tissue?

To support & protect the body and permit movement

What are 3 tissues one may find in plants?

Epidermal tissue, vascular tissue & photosynthetic tissue

What is the function of epidermal tissue?

To protect the surface of the plant

What is the function of vascular tissue?

To transport water & food substances

What is the function of photosynthetic tissue?

To feed the plant by photosynthesis

What is an organ?

"It's a no. of different tissues combined together which is able to perform a particular job due to the arrangement of tissue within it."

What are 5 organs one may find throughout the human body?

Brain, lungs, heart, stomach & kidneys

What is the function of the brain?

"It's responsible for co-ordinating the activities of the nervous system"

What is the function of the lungs?

"They're a pair of gaseous exchange organs found in the chest of mammals"

What is the function of the heart?

To pump oxygenated blood around the body

What is the function of the stomach?(2)

"It's a large muscular sac in the front part of the gut of a mammal which stores & digests food"

What is the function of the kidneys?(2)

To get rid of waste substances & control the amount of water in the body

What is an organ system?

Several organs which work together to perform a particular task form an organ system

Mention 2 examples of organ systems.

Circulatory & the digestive systems

What is cell specialisiation/ differentiation?

"It's when a cell changes their shape & form and turn intor particular types of cells depending on their location inside the body."

Which cells are produced from differentiation?

Nerve, muscle, sperm, root hair, photosynthetic, xylem & phloem cells

Mention 4 examples of specialised cells (not necessarily differentiated) in Homo Sapiens.

Ciliated cells, erythrocytes/red blood cells, neurones/nerve cells, epithelial cells, sperm cells & egg cells

What are the features & functions of the ciliated cell?

It has tiny hair-like protrusions called cilia which sweep mucus with trapped dust, debris & bacteria up the pharynx to prevent lung damage. It lines most of the trachea and bronchi.

What are the features & functions of the erythrocyte/red blood cell?

"It has a biconcave shape for increased surface area for oxygen absorption, it contains the red pigment haemoglobin (good attractant of oxygen) and it doesn't have a nucleus to maximise the space for haemoglobin. It's function is to carry oxygen from the lungs to the cells in need around the body."

What are the features & functions of the neurone (nerve cell)?

"It's function is to carry electrical impulses to and form the brain & spinal cord. It has a myelin sheath which provides electrical insulation, meaning that it helps the electrical impulse to pass fully through the neurones. It also has connections at each end."

What are the features & functions of the epithelial cell?

"It's found in the nephron proximal tube (forms part of the kidney) & contains lots of mitochondria for the re-absorption of substances to the blood stream through active-transport. It also has microvilli which increases the surface area of the cell surface membrane allowing the cell to absorb nutrients more quickly."

What are the features & functions of the sperm cell?

"It's main function is to fertilise the egg cell. It has enzymes in it's acrosome to help it digest the egg cells outer membrane and lots of mitochondria to provide it with energy. It also has a tail to help it swim towards the egg cell."

What are the features & functions of the egg cell?

"It's designed to be fertilised by a sperm cell as it contains half the genetic information needed for the offspring to form. It has a store fo food which provides nutrients to the developing cell."

Mention 4 specialised plant cells

Palaside, root hair, xylem & phloem cells

What are the main features & functions of the palaside cell?

"It has lots of chloroplasts with the green pigment chlorophyll, an elongated shape to increase surface area for sun-light absorption and found in the upper part of the leaf to be more exposed to sunlight. It's function is to carry out photosynthesis in the leaf."

What are the main features & functions of the root hair cell?

"It's function is to absorb water & minerals from the soil. It has a long extension which increases the surface area for water & mineral absorption and a large no. of mitochondria to provide it with energy when absorbing minerals by active transport"

What is the brief function of xylem & phloem cells?

Xylem transport water into the cell & phloem transport food substances into the cell

What are eukaryotic cells?

"Eukaryotic cells have membrane-bound organelles & genetic material enclosed in a nucleus. They're also found in multicellular organsims"

What are prokaryotic cells?

They're always unicellular (bacteria), don't contain any membrane-bound organelles and don't have a nucleus (some have plasmids(rings of DNA) instead)