B2 – Chapter 1: 1.1, 1.2, 1.4, 1.4, 1.5, 1.6

CELLS AND SIMPLE CELL TRANSPORT.

Light microscopes can recognise cells by magnifying them several hundred times, electron microscopes can magnify things several thousand times.

Structures of an animal and plant cells (All of which animal cells contain so do with plant cells, however plant cells have more features)- Nucleus: Controls the cell, contains genetic material & carry instructions to make new

cells/ organisms- Cytoplasm: Liquid gel which have chemical reactions needed to sustain life, controlled by

enzymes. - Cell membrane: Controls what goes in and out of the cell- Mitochondria: Oxygen is used and energy needed for respiration to take place- Ribosomes: where protein synthesis occurs

Things only plant/ algal cells contain: - Cell wall: To support the cell/strengthen it, contains cellulose- Chloroplast: Contain chlorophyll, allows photosynthesis to take place and absorb light to

make food (found in green plants of plant)- Permanent vacuole: Filled with cell sap, used to keep the cell rigid

Bacteria & yeast are single celled organisms but are smaller than yeast. A bacteria cell is different from both a plant and animal cell. It contains a cytoplasm and this is surrounded by a membrane and a cell wall. Genetic material is within the cell; however these are not in the nucleus. It has long strands of DNA, is circular and found in the cytoplasm.

Plasmids are small circular bits of DNA, they have flagellum (protein strand) which allows it to travel and is used in food such as cheese or some may cause disease.

A yeast cell has a nucleus that has the genetic information, cytoplasm and a cell wall and membrane. They reproduce by asexual budding (when yeast cells separates from the original).- They can survive for long periods of time due to aerobic respiration.

This is used to break down into sugars; they produce water and carbon dioxide as waste.

- Although, when a lack of oxygen is available, anaerobic respiration is required, this is when they break down sugar and produce ethanol and

carbon dioxide instead ( a process called fermentation)

Cells can be specialised to do a certain job, these include fat cells, root hair cells, blood and sperm cells.

Fat cells are used to store fat on your body if you eat more food than you need & if you need them if you are in short food supply.- These contain small amounts of cytoplasm and have large amounts of fat. - Little mitochondria as the cell requires a low amount of energy- Able to expand 1000x its normal size

Cone cells from human eyes make it possible for you to see colour. They are in light- sensitive layer of the eye. - Outer segment has chemicals and changes in coloured light. Energy is needed

to change it to its original form.- Middle segment withholds mitochondria, energy releases to reform the visual

pigment and let you see in colour.- Final part has a specialised synapse that connects to the optic nerve (nerve

carrying impulses to brain). An impulse is triggered once coloured light allows the change in visual pigment to occur. This impulse crosses the synapse

allowing the optic nerve to send messages to the brain.

Root hair cells found close to tips of growing roots. Helps absorb water and minerals. The xylem tissue carries it to the rest of plant.- Increased surface area to allow water to move up cell- Large permanent vacuole that allows osmosis to take

place quicker by the movement of water from the soil across the cell.

Sperm cells are released in order for an egg to be fertilised. They contain genetic material from the male parent. - Long tail is able to move side by side which helps it move along- Middle section contains mitochondria for energy

- The acrosome stores digestive enzymes foe breaking down the egg’s out layers through penetration

- Large nucleus contains genetic material in order for reproduction to take place.

In order for substance to move in and out of your body, diffusion needs to take place. This is vital for respiration as glucose and oxygen is needed to survive. Cells also need to get rid of waste products and chemicals in the body.

Diffusion is the spreading of particles from a high concentration to a low concentration which results in net movement. Particles bump into each other. This is across the concentration gradient. This occurs in gases or any substance in a solution. The greater the difference in concentration, the faster the rate of diffusion

Two examples of diffusion down concentration gradients:

The red blood cells are an example of a cell that is well-adapted for transport of molecules around the body – it carries oxygen around the bloodstream that is picked up by its haemoglobin proteins.

- Diffusion can happen over a cell membrane because membranes are described as being semi-permeable, meaning it will allow some

molecules to diffuse across it.

ORGANS IN PLANTS AND ORGANS IN ANIMALS

Multicellular (more than one cell) cells contain differentiated cells which are adapted to carry out a specific task. Differentiation is the process where cells are specialised such as a muscle cell.

- Tissues have groups of similar cells whereas organs have different tissues which carry out functions.

- Organs make up an organ system such as the digestive system which works together in an organism.

Function

Muscular tissue

Contracts, bringing about movement

Glandular tissue

Produces substances such as enzymes to enable chemical reactions and hormones to control functions

Epithelial tissue

Covers some parts of the body such as inside the gut& skin

Types of tissues and their functions

Plants also have tissues:- The epidermal tissue covers the surface for protection. - The mesophyll tissue has chloroplasts that allow photosynthesis to take place- To carry water and minerals ions up roots and leaves as well as dissolved food xylem and

phloem are transport tissues. - Plant organs include leaves for photosynthesis, stem to support leaves and flowers and

roots to take up minerals from the soil.

An example of an organ is the stomach. This is involves in the digestion of your food. It contains:

- Muscular tissue which churns up the food and the digestive juices of the stomach- Glandular tissue to produce the digestive juices that allow the food to break down- Epithelial tissue, which covers the inside and outside of the tissue Pancreas makes hormones to control the blood sugar and it makes enzymes which help

digest our foods.

Organs in the body have developed to allow exchange to take place: In lungs there is an exchange with gases. Into the blood digested food moves

from the small intestine Dissolved substances are filtered from

the blood into the kidney tubules. Some go back into the blood. All these adaptions allow exchange in material to be more efficient.

- The larger the surface area, the more quickly diffusion can take place

- Organs usually have good blood supply, allowing substances to go in and out, maintaining the concentration gradient which allows diffusion to happen rapidly.

The digestive system allows exchange of substances to take place. Food eaten is made up of insoluble molecules, meaning you can’t absorb this. They need to be broken down. They need to be broken down to be used by cells. This is called the digestive system.

- Digestive system > muscular tube, which squeezes food, goes the mouth and finishes at anus.

- Glands: pancreas and salivary glands, produce digestive juices containing enzymes and hormones (insulin), help break down food into smaller parts

- Stomach digests food as well as small intestine

- Live produces bile- Small intestine absorbs soluble food

and goes into bloodstream. This then gets transported around the body. Organ is adapted to have a large surface area, this increases diffusion from the gut to the blood

- In the large intestine, water is absorbed from the undigested food and into you blood, anything left is released as faeces. This goes through

muscular walls of the gut and squeeze through. This passes through the rectum and anus.