NET MOVEMENT OF PARTICLES from a region of HIGHER CONCENTRATION to a region of LOWER CONCENTRATION
Particles continue to diffuse until ..?
Concentration of particles is uniform throughout & until it reach an EQUILIBRIUM
Name the factors affecting rate of diffusion
Concentration gradient (steeper, faster); volume of particles(higher surface area to volume ratio, faster), Temperature(higher kinetic energy, faster); Thickness of barrier (lesser diffusion distance, faster)
What is the function of root hair?
what is the adaptation?
To absorb water and dissolved mineral salts from the soil or a particular planting medium.
The root hair cell has a LONG NARROW OUTGROWTH to INCREASE SURFACE AREA TO VOLUME RATIO for FASTER RATE OF DIFFUSION of water and dissolved mineral salts.
What is osmosis?
Net movement of WATER MOLECULES from a region of HIGHER WATER POTENTIAL to a solution of LOWER WATER POTENTIAL through a PARTIALLY PERMEABLE MEMBRANE
Describe what will happen to an animal cell in a hypertonic solution
The water molecules would ENTER the cell via osmosis, causing it to EXPAND and BURST
Describe what will happen to an animal cell in a hypotonic solution
The water molecules LEAVE the cell via osmosis, causing it to SHRINK in size. Little SPIKES appear on the cell membrane. The cell is CRENATED. The cell becomes DEHYDRATED and eventually dies.
Describe what will happen to a plant cell in a hypertonic solution
As water molecules enter the cell via osmosis, the VACUOLE INCREASES in size, and PUSHES CELL CONTENTS AGAINST THE CELL WALL [TURGOR PRESSURE]. The strong and inelastic cell wall exerts an OPPOSING FORCE. This prevents the OVER-EXPANSION OF CELLS; ENTRY OF MORE WATER MOLECULES; CELL FROM BURSTING. The cell is turgid.
Describe what will happen to a plant cell in a hypotonic solution
As water molecules leave the cell via osmosis, the VACUOLE DECREASES in size, CYTOPLASM SHRINKS FROM CELL WALL and the cell is PLASMOLYSED. This causes the plant to be FLACCID. If plant CELLS are PLASMOLYSED for too long, the PLANT starts to wilt and eventually dies.
What is active transport?
A process in which ENERGY RELEASED FROM RESPIRATION IS USED to MOVE PARTICLES of a substance, ACROSS A MEMBRANE, AGAINST a concentration gradient from a region of LOWER CONCENTRATION to a region of HIGHER CONCENTRATION
It means that humans being are large, complex and multi-cellular organisms which require a double circulation in order to get sufficient oxygen to the many cells in the body. BLOOD PASSES THROUGH THE HEART TWICE.
What is the pulmonary circuit?
The pulmonary circuit links the heart to the lungs. Deoxygenated blood rich in carbon dioxide is transported to the lungs for gaseous exchange via pulmonary arteries. After the blood has been oxygenated, it is then transported back to the heart by the pulmonary veins.
What is the Systemic circuit?
The systemic circuit links the heart to the rest of the body. When the heart pumps, oxygenated blood, that has returned from the lungs, leaves the left ventricle and will be sent to all pars of the body , transporting oxygen to the cells that need it for respiration. At the same time, carbon dioxide, which is a waste product of respiration, diffuses into the blood stream and is carried in the blood which returns to the heart via the superior vena cava (head,neck,arms) and the inferior vena cava (other body parts of the body except lungs).
What are the 6 characteristics of an artery?
Thick, elastic wall; carries oxygenated blood except pulmonary artery; carry blood away from heart; lumen is small; valves are absent, blood flows under great pressure & high speed
What are the 6 characteristics of a vein?
Thin, inelastic wall, carries deoxygenated blood except pulmonary vein; carry blood towards the heart, lumen is big, valves are present, blood flow is smooth and slow
What are the 4 characteristics of a red blood cell?
Biconcave, increase surface area to volume ratio; Contains Haemoglobin, which is a molecule which binds reversibly to oxygen, allowing it to carry oxygen to the parts of the body that require it; Flexible and elastic, to enable it to squeeze through narrow capillaries; Function: To carry oxygen gas around human body; nucleus is absent.
What are the 3 characteristics of a white blood cell?
Larger and rounder; Function: To fight against bacteria and foreign bodies entering body; nucleus is present
What is the function of platelets?
Helps in the clotting of wound. Insoluble fibrin threaads entangle the blood cells and the whole mass to form a clot. It becomes sticky, preventing excessive blood loss and entry of germs by sealing up the wound.
What is the function of the plasma?
Transport of blood cells, ions, soluble food substances, hormones, carbon dioxide, urea, vitamins, plasma proteins
What is the digestive equation for digestion of fats?
Fats ------(pancreatic & intestinal lipase)----------> glycerol and fatty acids
What happens to an enzyme when it is placed in a temp too low?
It will be inactive. It posesses little K.E. --> frequency of enzymes colliding with substrate is low
What happens to an enzyme when it is placed in a temp too high?
It will be denatured. Enzymes unable to catalyse any further as shape of enzyme is changed and active site is lost
Bile is made in _____________ but stored in _____________.
Liver; gall bladder
Function of bile?
EMULSIFY large fat globules into small flat globules, increasing surface area to volume ratio and makes them easier to digest
What happens if the Gall bladder is removed?
It stores bile juice temporarily. DIGESTION OF FATS IS AFFECTED if it's removed. As bile juice helps in BREAKING DOWN THE FATS INTO SMALLER FAT GLOBULES OR EMULSIFYING THE FATS. This is to INCREASE THE SURFACE AREA for the digestion of fats by enzymes PANCREATIC LIPASE AND INTESTINAL LIPASE
Name 3 ways in which absorption of food is made easier.
Presence of villi (increase SA to vol. ratio, increase rate of absorption); Wall of small intestine one-cell thick, shortens distance between wall and blood vessels); Small intestine is long, increase SA to vol. ratio
It is the fusion of two gametes (sperm and ovum) to form a zygote, then developing into an embryo
3 Sexually Transmitted Infections (STI)
Gonorrhea, Syphilis, AIDS (Acquired Immune Deficiency Syndrome)
Agent of transmission for Gonorrhea/Syphilis
Agent of transmission for AIDS
Name the mode of transmission of AIDS.
Close sexual contact, infected blood or blood products, sharing drug needles with an infected person, from an infected mother to infant in utero, during birth, or while breastfeeding
Male reproductive system
What are the 4 characteristics of sperm?
Has flagella; smallest cell in male body; produced in testes; able to move
Function of Testes (Singular:Testis)
Production of male gametes (sperms) and male sex hormones (testosterone); Lies in a pair of sacs called scrotal sacs (scrotum)
Why do testes lie outside the body?
The process of sperm production requires a temperature a few degrees lower than the body temperature
Function of sperm ducts
Transports matured sperms from testicle to the urethra (narrow tube within the penis) and out of the man's body during ejaculation
Function of Prostate gland
It is at the base of the urinary bladder. The prostate gland, together with some other glands, secretes a slippery fluid which mixes with the sperms. The fluid contains NUTRIENTS and ENZYMES that STIMULATE THE SPERM TO SWIM ACTIVELY. The sperm and fluid make up the SEMEN, which is released during ejaculation
Function of penis
The tissue in the penis has many spaces that can be filled with blood. During sexual intercourse the penis becomes hard and erect, allowing it to enter the vagina of a woman to deposit semen
Female reproductive system
What are the 4 characteristics of ovum?
No flagella; largest cell in the female body; produced in ovaries; not able to move
Function of Ovaries
Production of eggs or ova and hormones or chemicals which regulate menstruation and other aspects of health and well being; Releases one ovum every four weeks
Function of Oviducts/Fallopian tube
Site of fertilization; Transports ova away from the ovaries, has a funnel-like opening lying close to the ovary, making it easier for the egg to enter the oviduct
Function of Uterus
Also known as the Womb, it is where the foetus develops during pregnancy. Pear-shaped, has muscular walls. Its inner lining is soft and smooth. Part of this lining is sloughed off every month during menstruation
Function of Cervix
It is the 'neck' of the uterus, which supplies mucus to the vagina. It is also the site of deposition of sperms
Function of Vagina
Site which receives the penis during copulation. It is muscular and stretchable (forms part of birth canal)
Menstrual Cycle of the female reproductive system
What is ovulation?
Once a female reaches puberty, she will start to release ova from her ovaries, a process known as ovulation
What is menstruation?
The monthly discharge of dead ovum, broken uterus lining and blood via the vagina
When does ovulation occur
On the 14th day
What happens during ovulation?
1. On the 14th day, the walls of the uterus develop a spongy lining (endometrium), containing many capillaries. 2. This helps to prepare the uterus to accept a fertilized ovum. The ovum passes down the Fallopian tube.3. If the egg is fertilized, it is implanted in the endometirum and grows in the uterus. 4. The ovaries then stop releasing more ova until the baby is born.5. If the ovum is not fertilized, it passes through the uterus and the vagina and out of the vulva.
Factors that affect the menstrual cycle?
Stress, emotional disturbances, mental fatigue and illness affects the menstrual cycle. An unbalanced diet or malnutrition may cause the periods to become irregular or to stop completely (menopause).
Name 2 characteristics of Tubal Ligation
Female permanent contraceptive method; Cutting & Tying of oviduct. Prevents the ovum from fertilizing with the sperm. DOES NOT stop production of ovum.
Name 2 characteristics of Vasectomy
Male permanent contraceptive method; Cutting & tying of sperm duct. Prevents the sperms from mixing with semen, DOES NOT stop production of sperms.
Why is IUD a method of abortion?
Contraception or birth-control is to prevent fertilization. However, IUD DOES NOT prevent fertilization from occurring. Its working principle is to prevent the IMPLANTATION of zygote to the wall of the uterus. Hence, it is considered as abortion or deliberate ending of pregnancy.
Function of condom (Mechanical method)
Sheath over penis before sexual intercourse to trap sperms
Function of cap & diaphragm (mechanical method)
Fits over cervix of the uterus, prevents entry of sperms, usually used with spermicides
Function of birth-control pills (Hormonal method)
Prevent pregnancy by STOPPING OVULATION
Function of spermicides (Chemical method)
Contain CHEMICAL substances that kill sperms are put into the vagina before sexual intercourse