Y8 Biology (help me please) (copy)

Cells - Objectives 1 - 8

Definition

• smallest structural and functional unit of all living organisms

• building blocks of life

Cell theory

• all living things made up of cells

• cells are basic building blocks of life

• new cells are formed form the division of parent cells (mitosis)

Structures

• cell membrane

  • delicate membrane that surrounds the cell

  • regulates what enters and exits

• cytoplasm

  • watery jelly-like substance

  • contains dissolved substances and organelles

  • fluid part is called cytosol

• nucleus

  • membrane-bound sac that stores all the cell’s chromosomes/DNA

  • has pores

• mitochondria

  • powerhouse of the cell

  • helps convert glucose into energy that the cell can use

• ribosomes

  • builds protein for amino acids

  • can be free flowing or attached to the endoplasmic reticulum

• endoplasmic reticulum (ER)

  • smooth ER - do not have ribosomes attached and builds lipids and carbohydrates

  • rough ER - has ribosomes attached and stores protein made by ribosomes

• golgi apparatus

  • takes in sacs of raw material from ER and sends out sacs containing finished cell products

• lysosome

  • only in animal cell

  • sacs filled with digestive enzymes

  • digests worn out cells

  • digests food/nutrients absorbed by cell

• centrioles

  • pair of bundled tubes

  • organizes cell division

• cytoskeleton

  • made out of microtubules

  • found throughout cytoplasm

  • gives shape to cells and moves organelles around inside

next 3 for plant cells only

• cell wall

  • very strong, rigid, structure

  • made of cellulose

  • protects cells from rupturing

  • sits outside cell membrane

  • glued to other cells it is next to

• chloroplasts

  • contains chlorophyll - the chemical that allows photosynthesis to occur

  • carries out photosynthesis

• vacuole

  • huge, water-filled sac

  • permanent

  • keeps the cell pressurised

  • stores starch

  • animal cells also have vacuoles, but not permanent or big, and do not keep the cell pressurised

• Fungal cells have all of the animal organelles and a cell wall made of chitin

Prokaryotes and Eukaryotes

Prokaryotes

• organelles lack a membrane

• ribosomes are the only organelle

• genetic material floats in the cytoplasm

• circular DNA

• unicellular, smaller in size

• large number of organisms

Eukaryotes

• organelles covered by a membrane

• multiple organelles - including ribosomes

• have a nuclear membrane covering genetic material

• linear DNA

• can be unicellular or multicellular

• cells larger in size

• smaller number of organisms

Unicellular and Multicellular

Unicellular

• simple and composed of a singular cell

• i.e. yeast, amoeba, bacteria

Multicellular

• complex and of multiple cells that carry out different functions

• i.e. animals, plants, fungi

Microscopes - Objectives 9 - 14

Main parts of a light miscroscope

1. body tube - used to look at the specimen and magnify the image for the second time

2. revolving nosepiece - can be rotated clockwise or counterclockwise to change the magnification

3. objective lens (4x, 10x, 40x) - magnifies the image for the first time

4. stage clips - holds the slide in place

5. diaphragm - controls the amount of light that reaches the specimen

6. light source - projects up through the slide to illuminate the sample

7. ocular lens (eyepiece) - used to look at the specimen

8. arm - supports the microscope when carried

9. stage - where the specimen is placed for viewing

10. course adjustment knob - moves stage up and down for focusing

11. fine adjustment knob - moves the stage slightly to sharpen the focus

12. base - supports and provides stability for the microscope

Magnification

• As the field of view under the microscope increases, the magnification decreases

• As the field of view under the microscope decreases, the microscope increases

• to get the total magnification of a microscope, multiply the ocular lens magnification and the objective lens (i.e 10x ocular, 4x objective = 40x total)

• 1mm = 1000µm

• magnification = image size/actual size, (actual size being the µm given on the scale bar and the image size being the scale bar measured in mm and multiplied to get the µm. i.e. if the scale bar said 600µm, you would measure the length of the bar with a ruler and convert that to µm, x, and perform the sum x/600 to get the magnification)

Advantages and disadvantages between a light and an electron microscope

Mitosis - Objectives 15-18

Definition

• Mitosis is the simple duplication and division of a cell and all of its parts, and occurs for growth and repair

• It duplicates chromosomes and the 2 new cells (daughter cells) are identical

Stages - IPMAT

• Interphase - normal state of cell. DNA duplicates here.

• Prophase - When the cell gets the idea that it is time to divide, so it prepares by coiling the chromosomes, the mitotic spindle (what comes out the centrioles) begins to form, and the nuclear membrane begins to fade.

• Metaphase - The DNA lines up along a central axis and the centrioles send out specialised tubules that connect to the DNA

• Anaphase - When the separation begins. Half of the chromosomes are pulled to one side of the cell while half go the other way

• Telophase - When the chromosomes uncoil, the nuclear membrane reappears and the mitotic spindle breaks down.

• Telophase pt.2; Cytokinesis - when the cytoplasm divides

Digestive System - Objectives 19 - 26

Structural Units - general hierarchy, not specific to digestive system

• cell - a structural and functional unit (i.e a nerve cell)

• tissue - a group of cells with common structures/functions (i.e nervous tissue)

• organs - group of tissues working together for a common task (i.e brain)

• system - composed of several organs working together (i.e nervous system)

• organism - an individual containing several organ systems (i.e human)

Major Structures and their functions

• mouth

  • where food enters

  • coated in saliva which contains digestive enzymes that break down food (chemical digestion)

  • teeth used for chewing which breaks food into smaller pieces (mechanical digestion)

• pharynx

  • a tube where food and air travel through

  • when food is being swallowed, a special structure called the epiglottis closes over the entrance airway (trachea) so that food doesn’t go into the lungs

  • connected to the oesophagus

• oesophagus

  • a tube where food travels down after swallowing for digestion

  • food is moved down through peristalsis (wave-length muscular contractions)

• stomach

  • both chemical (acid breaking down complex molecules and a new substance is formed) and mechanical digestion (breaking down food through movement) occur here

  • bag-like muscular structure that stores and churns food to break it down

  • contains enzymes that start to break down food and hydrochloric acid that kills bacteria and sterilises food

• liver

  • makes bile for digestion of fats/lipids

  • processes the blood containing the nutrients absorbed from the small intestine

  • detoxifies potentially harmful chemicals in the blood

• gallbladder

  • stores and concentrates the bile made by the liver

  • releases the bile into the small intestine

• pancreas

  • produces enzymes for digestion

  • also produces insulin for controlling the absorption of glucose into cells

• small intestine

  • final point of chemical digestion

  • large surface area so contents released from the stomach come into contact with the enzymes to break them down

  • villi, microvilli, and circular folds contribute in increasing the surface area

  • once the food has been digested, the villi and microvilli lining this tube absorb the nutrients and send them into the bloodstream

• large intestine

  • vitamins and minerals are absorbed

  • waves or peristalsis move undigested food waste through this tube

  • waste becomes more solid as it moves through this tube due to the absorption of water from the waste back into the body

• rectum

  • stores the waste (faeces) leftover after digestion

• anus

  • controls the process of defecation and gets rid of waste

Key functions

• ingestion - taking in food

• digestion - breaking food down into molecules small enough to be absorbed

  • difference between chemical and mechanical digestion - chemical digestion uses enzymes to break down food into smaller, absorbable molecules and produce a new substance when doing this, while mechanical digestion breaks down food physically like chewing and churning.

• absorption - absorbing the nutrients

• egestion/defecation - eliminating undigested waste product

Nutrients in food

Importance of enzymes

• they break down important components in food so that they are easier to absorb

• speed up chemical reactions in living organisms

• without them, many processes would occur to slowly to sustain life

Comparing digestive systems

• carnivores

  • short digestive tracts

  • sharp teeth

  • strong digestive enzyme

• herbivores

  • long digestive tracts

  • flat teeth

• omnivores

  • shorter digestive tracts than herbivores but longer than carnivores

  • range of digestive enzymes

  • range of sharp and flat teeth

Why do they have different digestive systems?

• due to difference in diet

• carnivores - sharp teeth to tear and hold down prey; since meat is easy to digest, they have strong enzymes to break it down and a short digestive tract to process food quickly

• herbivores - flat teeth to grind fibrous plants; long digestive tracts to maximise nutrient absorption

• omnivores - eat both meat and plants, so their digestive systems are in between carnivores and herbivores

Respiratory System - Objectives 27 - 31

Major Structures and their functions

• nasal cavity

  • the air enters through the nostrils

  • filtered by hairs

  • warmed, humidified

• larynx

  • voice box

  • reinforced with cartilage to help protect airway

  • keeps fluid and food from entering the airway

• trachea

  • windpipe

  • rings of cartilage that maintain the shape to prevent it from closing

  • cilia helps sweep particles and fluid from getting into the lungs

  • forks into the bronchi

• bronchi

  • each bronchus leads into a lung and branches into smaller and smaller bronchioles

  • distributes air into bronchioles

• bronchioles

  • during

• alveoli

  • small, balloon like sac that is 200-500µm in diameter

  • found at the end of bronchioles in lungs

  • each alveolus plays an important role in letting oxygen and carbon-dioxide move into and from the blood stream during inhalation and exhalation

  • gas exchange occurs here - where oxygen moves from the lungs to the bloodstream, while carbon-dioxide simultaneously passes from the blood to the lungs

  the rest are not where the air flows through, but parts that are still included in the respiratory system

• lungs

  • where the two bronchi lead to, and where the bronchioles and alveoli are found

• intercostal muscles

  • located in the space between the ribs

  • during inhalation, the external intercostal muscles contract and lift the ribs upward, expanding the chest cavity and creating negative pressure, which draws air into the lungs.

  • during exhalation the internal intercostal muscles contract, they pull the ribs downward, reducing the chest cavity and forcing air out of the lungs 

• ribs

  • protects the lungs

  • allows for expansion and contraction during breathing

• sternum

  • breast bone

  • central bone in the ribs (therefore same function)

Inhalation and exhalation

• When you breathe in:

  • intercostal muscles between the ribs contract, pulling the chest walls up and out

  • diaphragm muscle below the lungs contracts and flattens, increasing the size of the chest

  • lungs increase in size, so the pressure inside them falls. This causes air to rush in through the nose or mouth

• When you breathe out:

  • intercostal muscles between the ribs relax so that the chest walls move in and down

  • the diaphragm muscle below the lungs relaxes and bulges up, reducing the size of the chest

  • the lungs decrease in size, so the pressure inside increased and the air is pushed up the trachea and out through the nose or mouth

Gas exchange

• air rich in oxygen enters the lungs and reaches the alveoli

• oxygen diffuses from the alveoli into the blood in the capillaries, driven by the partial pressure gradient

• carbon dioxide diffuses from the blood in the capillaries into the alveoli, also driven by the partial pressure gradient 

• air rich in carbon dioxide is exhaled from the lungs. 

• oxygen-rich blood is transported to the tissues throughout the body, where oxygen is released to cells for cellular respiration. 

• carbon dioxide, a waste product of cellular respiration, is transported back to the lungs for exhalation

Comparing Fish and Animal respiratory system

• Animal

  • have a mouth, a pharynx, lungs, a trachea, bronchi, bronchioles, diaphragm, alveoli

• Fish

  • d support 1 or 2 filaments

  • spiracles that are an opening used to draw water into the gills for respiration

  • most-efficient system for exchanging water and carbon dioxide between blood and water

• differences reflects the adaptations to the environment

Circulatory System - Objectives 32 - 38

• all circulatory systems consist of a pump, carrier, fluid, and tubes/vessels

4 components of blood

• plasma

  • makes up just over half of the blood

  • water based-liquid

  • white blood cells, red blood cells, platelets all in this solution

• red blood cells (erythrocytes)

  • carry oxygen from the lungs to the rest of the body

  • contains haemoglobin that carries the oxygen and the carbon dioxide to and from the heart/lungs

• white blood cells (leukocytes)

  • help fight infections and aid in the immune system

• platelets (thrombocytes)

  • broken down parts of cells

  • help in blood clotting

  • form scabs

Types of circulatory systems

• closed circulatory system

  • blood is always contained in the vessels and never directly makes contact with the body’s tissues

• double circulatory system

  • blood pumps through the heart twice on every full circuit of the body and involves two distinct circuits - the pulmonary circulation and the systemic circulation

• pulmonary circulation

  • pumps blood to the lungs from the heart, and then returns to the heart again

• systemic circulation

  • pumps blood to the rest of the body and then back to the heart

Arteries, veins, and capillaries

• arteries

  • carries oxygenated blood away from the heart and to the rest of the body

  • very strong and thick walls to cope with the high pressure of the blood flowing through them

  • thick walls stretch and then flex back into place because of the elastic fibres in the walls

• capillaries

  • arteries divide into smaller and smaller vessels - smallest being the capillaries

  • very small and penetrate every part of the body

  • takes nutrients and oxygen to cells and takes waste products away

  • very thin walls so the substances can get in and out very quickly

• veins

  • capillaries eventually join again and form veins

  • carries deoxygenated blood back to the heart

  • by the time blood gets to the veins, it is at a lower pressure than it was in the arteries

  • have thinner, less strong walls compared to the arteries

  • have valves to stop blood from flowing backwards

Heart

• located in the centre of your chest in between the lungs

• 4 chambers - 2 atriums, 2 ventricles

Sexual and Asexual Reproduction - Objectives 41 - 49

• reproduction is the biological process by which new individual organisms, or "offspring," are produced from their "parent" or parents, ensuring the continuity of species

Asexual and Sexual reproduction

• Difference between asexual and sexual reproduction - asexual reproduction only requires one parent and produces a genetically identical offspring, whereas sexual reproduction requires 2 parents and produces a genetically unique offspring through the fusion of gametes

• asexual reproduction examples

  • plants - vegetative propagation (when new plants grow from parts of the parent plant such as stems, leaves, or roots, without the use of runner, i.e. strawberries)

  • animals - parthenogenesis (when an unfertilised egg develops into a new individual without fertilisation by sperm, allowing females to reproduce without males, i.e. wasps)

Disadvantages and advantages

Reproductive system of a plant

Structures:

• petals

  • colourful and sweet

  • purpose is to attract pollinators

• stalk/stem

  • holds up flower and gives support

  • also provides a highway for water and food to supply the plant with its needs

• nectary

  • where nectary (sweet liquid) is produced by plants to attract pollinating animals

• ovary

  • protects ovules

• ovules

  • once they are fertilised they become seeds, and the ovary will become a fruit that protects the seed

• receptacle

  • thickened part of a stem from which the flower grows

  • also where the flower attaches to the stalk

  • some cases it becomes a part of the fruit after fertilisation

• style

  • stalk of the pistil that rises up from the ovary

• stigma

  • part of the pistil that catches the pollen

  • sticky substance on the tip to catch

  • shaped different depending on the type of flower

• pistil

  • female part of the flower

  • contains the ovary, ovules, stigma, style

• stamen

  • male part of the flower

  • made of filament and anthers

  • also responsible for producing pollen

• filament

  • stalk that holds up the anther

• anther

  • located on the top of the filament and holds the pollen until the they mature

  • once the anthers mature, they burst, releasing the pollen

• pollen

  • fertilising element of flowering plants

  • made of fine, powdery grains or spores

Pollination v Fertilisation

• Pollination is the transfer of pollen from the male anther to the female stigma, while fertilisation is the fusion of male and female gametes (sperm and egg) to form a zygote, which eventually develops into a seed

Human reproductive system

Female

• ovary

  • 2 ovaries

  • primary female reproductive organs

  • produce and release ova

• oviduct

  • 2 uterine tubes that extend from the ovaries and lead to the uterus

  • the fimbriae at the ends of the tubes direct the ovum into tubes where ciliated epithelial cells and muscle contractions guide the ovum down to the uterus

• clitoris

  • made up of erectile tissue, nerves an blood vessels

  • sensitive to touch and when stimulated becomes the ‘erect’ and engorged with blood

• labia minora

  • two folds

  • lack fatty tissue and pubic hair

  • inner folds of skin that surround the clitoris and protect the urethral opening

• labia majora

  • two folds

  • consist of fatty and fibrous tissue that protects the entrance to the vagina

  • many glands secrete oil keeping the inner surface moist

  • outer surface covered in pubic hair

• vagina

  • canal that extends from the cervix and leads outside the body

  • lined with mucous membranes

  • receive the penis during intercourse

  • changes to become the birth canal during birth

• cervix

  • neck of the uterus

  • protrudes into the vagina

  • where the semen is deposited during intercourse

• uterus

  • composed of smooth muscle

  • lined with the endometrium

  • blastocyst implants here during pregnancy and as it grows the uterus expands

Male

• seminal vesicles

  • 2 seminal vesicles

  • secrete fluid that makes up most of semen

  • thick fluid contains sugars to nourish the sperm

• prostate gland

  • secretes fluid that is part of semen

  • thin, milky, alkaline fluid

• bulbourethral glands

  • 2 glands secrete a clear mucus just before the semen is ejaculated

  • acts as a lubricant

• scrotum

  • skin covered pouch

  • holds the testes

  • internally divided into 2 pouches

  • muscles can move it away or towards the body

• testes

  • 2 primary male reproductive organs

  • produce sperm

• epididymas

  • folded tube where sperm are stored and matured

  • 5-6m long when stretched and sits behind the testes

• erectile tissue

  • have a lot of spongy spaces filled with blood that cause the penis to erect

  • once erect the penis can be inserted into the vagina

• urethra

  • tube that runs through the penis

  • can transport urine or semen out of the body

• vas deferens

  • 2 tubes

  • connects the epididymis of each testis to the urethra

  • carries sperm away from the testes to the urethra