Sec 2 Flashcards
Chapter 10
What are two essential substances that cells require to survive?
Nutrients and oxygen
Chapter 10
Explain the need for a transport system in multicellular organisms.
Since there are as much as billions of cells in a multicellular organism, most cells lie far away from the source of essential substances and a transport system is an efficient way for cells to obtain these essential substances.
Chapter 10
What is the similarity and difference between diffusion and osmosis?
They are similar in how both processes involve the overall movement of particles from a region of higher concentration to a region of lower concentration. Osmosis is the overall movement of water molecules only while diffusion is the overall movement of all particles through a partially permeable membrane.
Chapter 10
How is diffusion used to ensure that there is enough oxygen in the cell?
Since the cell is constantly using up oxygen, the concentration of oxygen inside the cell is lower than the concentration of oxygen outside the cell. The diffusion gradient is maintained which means that oxygen keeps diffusing into the cell and thus, diffusion ensures that there is enough oxygen in the cell.
Chapter 10
How is the exchange of gases in a leaf during photosynthesis an example of diffusion?
In the presence of light, photosynthesis occurs where carbon dioxide is used up and oxygen is produced by the leaf. Carbon dioxide diffuses in and oxygen diffuses out. These processes thus show that diffusion plays a pivotal role in the exchange of gases in a leaf during photosynthesis.
Chapter 10
What is the definition of osmosis?
Osmosis is the net/overall movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane.
Chapter 10
What is the definition of diffusion?
Diffusion is the overall movement of particles from a region of higher concentration to a region of lower concentration.
Chapter 10
What is water potential?
Water potential can be thought of as the “concentration” of water in a substance.
Chapter 10
What is the difference between a cell bursting and crenation?
A cell bursts when it is placed in a solution which has higher water potential as compared to the water potential in cell’s cytoplasm. Water moves from the solution into the cell via osmosis, causing the cell to expand and burst. A cell crenate when it is placed in a solution which has lower water potential as compared to the water potential in cell’s cytoplasm. Water moves from the cell into the solution via osmosis, causing the cell to crenate.
Chapter 10
How do animals avoid the bursting and crenation of cells?
Animals maintain roughly a similar solute concentration both inside and outside the cell
Chapter 10
What is the difference between a plant cell becoming plasmolysed and turgid
The cell sap of the plant cell has to have a lower water potential than the surrounding solution which means that water will diffuse from the solution into the cell and the plant cell would then expand and become turgid. While the cell sap of the plant cell has to have a higher water potential than the surrounding solution which means that water will diffuse from the cell into the solution which means that the cytoplasm will shrink away from the cell wall, becoming plasmolysed.
Chapter 10
What is a transport system in a plant made of?
The roots and vascular bundles.
Chapter 10
What are the two flows in the plant transport system?
The upward flow of water and mineral from the roots to the leaves and there is a downward flow of food molecules from the leaves to the roots.
Chapter 10
How are water and mineral salts taken into a plant?
Water and mineral salts from the soil diffuses into root hair cells which are located at the ends of roots.
Chapter 10
What are the functions of the xylem tissue and phloem tissue respectively?
The xylem tissue transports water and minerals from the roots to the leaves while the phloem tissue is in charge of the transport of leaves to the roots.
Chapter 10
What is the definition of transpiration pull?
Transpiration is the upward pull of water as water is evaporated from the leaves which means that there is a low water potential at the leaves and water will move into the leaves via osmosis from the roots.
Chapter 10
In the phloem tissue, what is the overall flow of the transport of food substances?
The overall flow of the transport of food substances inside the phloem is downwards.
Chapter 10
State two features of a root hair cell.
It is a long outgrowth of a root cell which increases surface area to volume ratio. The cell vacuole of a root hair cell contains cell sap which is concentrated with mineral salts.
Chapter 10
Why is it that as organisms get bigger, simple diffusion/osmosis is no longer enough to supply the needs of the organism?
As organisms get bigger, the surface area to volume ratio gets smaller which means that it is not efficient to use simple diffusion and osmosis for the supply of essential substances and nutrients as these essential substances and nutrients are unable to reach the cells fast enough for cellular respiration and waste is not able to be disposed of fast enough.
Chapter 10
What are the components of blood?
Plasma, red blood cells, white blood cells and platelets.
Chapter 10
What is plasma made of and what is the function of it?
Plasma is made of mainly water and its function is to act as a solvent for many substances and transport them from one part of the body to another.
Chapter 10
What are 2 characteristics of red blood cells and what is their function?
The characteristics of red blood cells is that they have a biconcave shape and that they do not have a nucleus. Red blood cells take in and release oxygen through diffusion.
Chapter 10
State 10 components of the human transport system
Blood which contain red blood cells, white blood cells, plasma and platelets, blood vessels, veins, arteries, capillaries and the heart
Chapter 10
State and explain the function and importance of the heart
The heart is a muscular pump that keeps the blood circulating quickly and continuously, ensuring that blood is delivering oxygen and nutrients to your cells and removing waste products.
Chapter 10
State and explain the function and importance of veins
Veins are a type of blood vessel that is thin and has less elastic walls compared to arteries and carry mostly de-oxygenated blood towards the heart.
Chapter 10
State and explain the function and importance of arteries
Arteries are a type of blood vessel that is thick, elastic and has muscular walls to withstand high pressure as oxygenated blood is carried away from the heart.
Chapter 10
State and explain the function and importance of capillaries
Capillaries are a type of blood vessel which very thin, has one-cell thick walls to allow easy diffusion of substance. Capillaries connect arteries to veins and form a vast network linking to the cells of the body. Capillaries carry oxygen and nutrients to the cells and carry carbon dioxide and waste produced away from the cells.
Chapter 10
State and explain the function and importance of white blood cells
White blood cells are involved in defending the body against both infectious diseases and foreign materials. They are produced in the bone marrow and have a short lifespan.
Chapter 10
State and explain the function and importance of platelets
Platelets are irregularly shaped cell fragments that form clots to stop excessive bleeding.
Chapter 10
Describe the process of double circulation
Double circulation in the human body is like two “loops” of blood flow and the heart is like two pumps, maintaining the loops. One part pumps deoxygenated blood to the lungs to get rid of carbon dioxide and gain oxygen while the other part pumps this re-oxygenated blood to the rest of the body.
Chapter 10
Why must the human transport system work with other organ systems?
The human transport system, which is the circulatory system, supplies oxygen and nutrients to our bodies by working with the respiratory system. At the same time, the circulatory system helps carry waste and carbon dioxide out of the body.
Chapter 11
State the three main types of nutrients in food which can also be used to produced energy
Carbohydrates, proteins and fats/lipids.
Chapter 11
State 3 reasons why we need food
We need food to provide us with energy for our daily activities such as walking, grow new cells and tissues and repair worn-out tissues
Chapter 11
State and explain how digestion is important in allowing food molecules to be broken down and absorbed by the body through diffusion.
Since most food that we eat is made up of large, complex and insoluble molecules, the molecules cannot be absorbed by the body as they are too large to cross the partially permeable surface membrane. As such, the body needs to break down these molecules into small and soluble forms that can diffuse from the digestive system into the bloodstream and to other cells.
Chapter 11
State some sources of carbohydrates, proteins and lipids that can be found in common foodstuffs
Carbohydrates can be found in rice, proteins can be found in meat and lipids can be found in butter
Chapter 11
State the characteristics and functions of carbohydrates for the human body
Carbohydrates can be found in the form of starch, sugar or cellulose and can be soluble or insoluble in water. Carbohydrates provide an immediate source of energy and also makes up part of the fibre that the body cannot digest. Fibre passes out undigested and forms the bulk of our faeces.
Chapter 11
State the characteristics and functions of fats/lipids for the human body
Fats/lipids are made up of glycerol and fatty acids and is insoluble in water. Fats/lipids are mainly used as a storage of energy and prevents the body from losing too much heat.
Chapter 11
State the characteristics and functions of proteins for the human body
Proteins are made up of several small molecules called amino acids and can be soluble or insoluble in water. Proteins are mainly used to make new cells for body growth and repair worn-out tissue. Proteins is also used to make more complex proteins called enzymes.
Chapter 11
State and explain the function and importance of enzymes in digestion.
Enzymes are protein molecules that speed up the chemical digestion of the food molecules.
Chapter 11
State 5 five characteristics of enzymes
Enzymes are complex proteins that speed up the rate of chemical reactions. Enzymes remain unchanged at the end of the reaction. Enzymes are specific in their action and only speed up one kind of reaction. Enzymes are sensitive to temperature and pH. Only a small amount is required to affect a large amount of reactants.
Chapter 11
How does temperature affect the enzyme
If the temperature is too low, the enzyme will be inactive but if the temperature is too high, the enzyme will be denatured and lose its unique protein molecule shape, and will stop working as a result.
Chapter 11
How does pH affect the enzyme
Enzymes have an optimum pH level and can only function within a narrow pH range. Outside this range, denatured will occur
Chapter 11
Identify what enzyme acts on starch, maltose, proteins, and fats/lipids respectively and state what are the final products of digestion.
Amylase acts on starch which produces maltose, maltase acts on maltose which produces glucose, protease acts on proteins which produces animo acids and lipase acts on fats/lipids which produces fatty acids and glycerol.
Chapter 11
Name the 5 stages of digestion in order
Chewing, digestion in the stomach, digestion in the small intestine, absorption and defaecation.
Chapter 11
Identify the 6 parts of the alimentary canal
Mouth, oesophagus/gullet, stomach, small intestine, large intestine and anus.
Chapter 11
What happens in the mouth after eating food
The teeth cuts and grinds the food into smaller, pieces, increasing the surface area to volume ratio. The salivary glands which contains enzymes such as salivary amylase digests starch into maltose. The tongue pushes food around the mouth while we chew, and to the back of the mouth and into the oesophagus.
Chapter 11
What happens in the oesophagus after eating food
The oesophagus is a muscular tube about 25cm long. It transports food down through the process peristalsis. The muscles of the oesophagus contract above the ball of food, pushing it down. Muscles relax below the ball of food, widening the tube for it to move down.
Chapter 11
What happens in the stomach after eating food
The muscles of the stomach contract and relax to break down the food into even smaller pieces, and mix the food with gastric juices. Mixing is important as the gastric juices contain enzymes like protease, as well as hydrochloric acid.
Chapter 11
What are the functions of hydrochloric acid in the stomach
Hydrochloric acid creates and acidic environment which is the optimal pH for the proteases in the stomach to work and help kill bacteria.
Chapter 11
What happens in the small intestine after eating food
Partially digested from the stomach moves to the small intestine, which is aided in digestion by and connected to the liver and gallbladder, and the pancreas. Food is mixed with bile, intestinal juice and pancreatic juice in order to complete digestion. The final molecular products of digestion are then absorbed into the bloodstream here
Chapter 11
What digestive fluid does the liver, small intestine and pancreas respectively, and what enzymes are inside this digestive fluid
The liver produces bile which contains no enzymes, the small intestine produces intestinal juice and contains the enzymes maltase, protease and lipase and the pancreas produces pancreatic juice and contains the enzymes pancreatic amylase, protease and lipase.
Chapter 11
Describe the process of emulsification
Emulsification is the process where large fat droplets are physically digested by bile which is a digestive fluid produced in the liver into smaller fat droplets.
Chapter 11
How is food absorbed into the bloodstream in the small intestine?
After physical and chemical digestion are completed in the small intestine, the food molecules are absorbed into the bloodstream through the processes like diffusion. Only small food molecules pass through the walls of the small intestine and blood vessels. The small food molecules enter the bloodstream and are transported throughout the body.
Chapter 11
What happens in the large intestine when after eating food
Undigested food from the small intestine passes into the large intestine, where no digestion occurs. In the colon, water, mineral salts, and any remaining nutrients are absorbed. The rectum stores what is left as faeces, which leave the body through the anus in the process of defecation.
Chapter 11
Identify 5 digestive juices and how they contribute to the digestive process
Saliva contains salivary amylase that digests starch into maltose. Gastric juices contain the enzyme protease that digests proteins as well as hydrochloric acid. Bile helps in physically breaking down large fat droplets into smaller fat droplets in a process called emulsification. Intestinal juice contains the enzymes maltase which digests maltose, protease that digests proteins and lipase which digests fats/lipids. Pancreatic juice contains the enzymes pancreatic amylase which digests starch, protease which digests proteins and lipase which digests fats/lipids.
Chapter 12
What is reproduction?
It is the process by which organisms produce new organisms like themselves.
Chapter 12
Why is reproduction important?
Reproduction ensures the transfer of genetic information from one generation to another, and the continuity of a species.
Chapter 12
State and explain the function and importance of the sperm duct
The sperm duct is a muscular tube that carries sperms from the testes to the urethra.
Chapter 12
State and explain the function and importance of the male sex glands
The male sex glands secrete fluids containing nutrients and enzymes. The nutrients and enzymes provide the sperms with the energy to move.
Chapter 12
State and explain the function and importance of the penis
The penis becomes erect when sexually excited. Sperms are ejaculated through the penis during sexual intercourse.
Chapter 12
State and explain the function and importance of the urethra
The urethra is a tube which leads to the outside of the body through the penis. During sexual intercourse, sperms pass from the testes, into the sperm ducts and then into the urethra. The sperms pass to the outside of the body through the urethra.
Chapter 12
State and explain the function and importance of the testis (plural: testes)
The testes produce sperms and male sex hormones
Chapter 12
State and explain the function and importance of the scrotum
The scrotum is a sac outside the body that holds each testis and provides an environment where the sperms can develop at their ideal temperature.
Chapter 12
Why does the male reproductive cell have a tail?
The male reproductive cell has a tail as it the movement of the tail helps it to swim towards the female reproductive cell.
Chapter 12
State and explain the function and importance of the fallopian tube/oviduct
The fallopian tube/oviduct is a muscular tube connecting the ovary to the uterus. The wall of the oviduct contracts to push the egg along the oviduct towards the uterus.
Chapter 12
State and explain the function and importance of the ovary
The ovary produces eggs and female sex hormones.
Chapter 12
State and explain the function and importance of the uterus
The uterus is a pear-shaped organ with thin muscular walls. The inner surface of the uterus is covered with a layer called the uterine lining. This is also the site where fertilised embryo will develop
Chapter 12
State and explain the function and importance of the cervix
The cervix is a ring of muscle at the lower end of the uterus.
It is kept closed during pregnancy and widens during childbirth.
Chapter 12
State and explain the function and importance of the vagina
The vagina is a muscular tube. It joins the cervix to the outside of the body. It is also where sperm is deposited and through which the baby is born.
Chapter 12
State and explain the female reproductive cell and its characteristics
The female reproductive cell is an egg and it contains a nucleus.
Chapter 12
Define puberty
Puberty is the period when an adolescent becomes capable of sexual reproduction.
Chapter 12
At what ages does puberty start
Ages 10-14
Chapter 12
Why do people grow more during puberty?
During puberty, the body produces a higher amount of growth hormones
Chapter 12
What body systems are affected at the end of puberty for each gender?
For boys, they will have heavier bones and an increase in muscle growth. For girls, they will experience an increased amount of fat tissues at the breasts, hips and pubic region.
Chapter 12
State 5 effects of puberty for boys and 4 effects of puberty for girls
Boys will experience the growth of facial hair, the enlargement of the voice-box which leads to the deepening of the voice, the increase in the size of the penis and testes, the production of sperm and ejaculation occurs and hair starts to grow in the pubic region. Girls will experience hair growth in the armpits, enlargement of the breasts and uterus while the hips broaden, the menstrual cycle begins and hair starts to grow in the pubic region.
Chapter 12
Define menstruation
Menstruation is the discharge of the broken down tissues of the uterus, unfertilised egg and blood.
Chapter 12
State the 4 stages of the menstrual cycle
Menstruation, repair and growth of the uterine lining, ovulation and the further thickening of the uterine lining
Chapter 12
From which days does menstruation occur during the menstrual cycle
Days 1-5
Chapter 12
From which days does the repair and growth of the uterine lining occur during the menstrual cycle?
Days 6-10
Chapter 12
From which days does ovulation occur during the menstrual cycle?
Days 11-17
Chapter 12
From which days does the further thickening of the uterine lining occur during the menstrual cycle?
Days 18-28
Chapter 12
State and explain the repair and growth of the uterine lining during the menstrual cycle
The uterine lining grows thicker and becomes very rich in blood capillaries.
Chapter 12
Define ovulation
When a mature egg is released into the fallopian tube/oviduct
Chapter 12
Why does the uterine lining remain thick during days 18-28 of the menstrual cycle?
The uterine lining remains thick to supply the embryo with nutrients and oxygen for growth
Chapter 12
What happens during sexual intercourse?
During sexual intercourse, the erect penis is inserted into the vagina. The penis ejaculates semen (which contains sperm) into the upper end of the vagina. The sperms will then swim up to the uterus into the oviducts and one of the sperms may get to fuse with the egg cell.
Chapter 12
Define fertilisation
Fertilisation is the process where the nucleus sperm fuses with the nucleus of the egg.
Chapter 12
How does a woman get pregnant?
When sperm is deposited in the vagina during sexual intercourse, the sperm will travel up the uterus through the oviduct to the egg. If an egg is present in either oviduct, fertilisation may take place and the nucleus of the sperm and nucleus of the egg fuse. The fertilised egg divides repeatedly to form a ball of cells called the embryo. The embryo moves into the uterus and is implanted in the uterine lining and thus, the woman is pregnant.
Chapter 12
What happens during pregnancy?
During pregnancy, the embryo develops into a foetus or unborn baby.
Chapter 12
What happens during birth?
At the end of a pregnancy, the muscles of the uterus contract to push out the fully formed baby, the cervix enlarges to allow the baby to pass through and thus, the woman gives birth.
Chapter 12
Define heredity
Heredity is a process by which characteristics are passed down genetically from one generation to the next.
Chapter 12
What is premarital sex?
Premarital sex is the act of having sexual intercourse before a couple is married.
Chapter 12
What problems come with premarital sex?
Unwanted pregnancies and sexually transmitted diseases
Chapter 12
What is abortion?
Abortion is the deliberate termination of a pregnancy.
Chapter 12
When does an abortion usually carried out?
Abortion is usually carried out within the first 12 weeks of pregnancy.
Chapter 12
What are 3 reasons for abortion
The child may be born physically or mentally handicapped. The mother is physically and/or mentally incapable of supporting the child. The unwanted pregnancy resulted from rape.
Chapter 12
How is an abortion carried out?
During an abortion, a doctor surgically removes the embryo or foetus from the uterus.
Chapter 12
Why are birth control methods used and what do they prevent?
Birth control methods are used to prevent pregnancies through preventing ovulation, fertilisation or the implantation of the embryo.
Chapter 12
Identify 5 methods of birth control
Not having sexual intercourse at all (abstinence). Withdrawal of the penis just before ejaculation. The rhythm method. The use of chemicals such as spermicides and contraceptive pills. The use of mechanical devices such as condoms, diaphragms and intra-uterine devices.
Chapter 12
What is the temporary birth control method Rhythm method?
Couples who practise this method do not have sexual intercourse during the fertile period (ovulation) of the woman’s menstrual cycle.
Chapter 12
What is the temporary birth control method of using spermicide?
Spermicide is a chemical that kills or blocks sperms from entering the uterus. It comes in gel form, aerosol foams and foaming tablets and is inserted into the vagina before sexual intercourse. However, it is not reliable when used on its own and is usually used with a condom or diaphragm.
Chapter 12
What is the temporary birth control method of using a diaphragm/cap?
The diaphragm is a dome-shaped rubber cup with an elastic rim. It is inserted into the vagina and placed over the cervix. The diaphragm is impermeable to sperms and so, prevents sperms from entering the uterus. Hence fertilisation does not occur.
Chapter 12
What is the temporary birth control method of using a condom?
A condom is a thin rubber tube used to cover the erect penis before sexual intercourse. It is impermeable to sperms and hence, sperms cannot enter the uterus and fertilisation will not occur. It is also impermeable to bacteria and viruses. This also protects the user from getting sexually transmitted diseases.
Chapter 12
What is the temporary birth control method of using an Intra-uterine device (IUD)
The IUD is a piece of plastic or metal that is inserted into the uterus by a doctor. IUDs can also come in different forms. The IUD disrupts the function of the uterus by preventing the embryo from implanting in the uterus lining. This method provides effective protection for a long period of time.
Chapter 12
What is the temporary birth control method of using contraceptive pills
Contraceptive pills contain certain female sex hormones which prevent ovulation. They disrupt the function of the ovary by preventing the release of a mature egg each month. These pills must be taken under a doctor’s prescription and are reliable when a woman adheres to the instructions. However, she may suffer from some side effects.
Chapter 12
Identify 2 permanent birth control methods
Vasectomy and tubal ligation
Chapter 12
Why are permanent birth control methods permanent?
Permanent birth control methods permanently prevent fertilisation by disrupting the functions of parts of the reproductive system.
Chapter 12
What is the permanent birth control method of using vasectomy?
Vasectomy involves tying and cutting part of both sperm ducts during surgery. This disrupts the function of the sperm ducts. Sperms will not be ejaculated during sexual intercourse and thus the male will not be able to make his partner pregnant and thus fertilisation will not occur since sperms are absent.
Chapter 12
What is the permanent birth control method of using tubal ligation?
Tubal ligation involves tying and cutting both oviducts during surgery. This disrupts the function of the oviduct and prevents sperm cells from meeting the egg cell. Thus, fertilisation will not occur.
Chapter 12
What is a sexually transmitted infection?
An infection transmitted from one person to another through sexual intercourse is called a sexually transmitted infection (STI)
Chapter 12
Identify 3 sexually transmitted infections
Human Immunodeficiency Virus (HIV), Syphilis and Gonorrhoea
Chapter 12
How does one get a sexually transmitted infection?
During sexual intercourse, bodily fluids are exchanged in the reproductive systems. Bacteria or viruses in those bodily fluids can enter the circulatory system of his or her sexual partner through their sexual reproduction system. Some sexually transmitted infections may also be spread through contaminated blood or childbirth.
Chapter 12
Explain what Human Immunodeficiency Virus (HIV) does to the body and is it curable or treatable?
HIV attacks the immune system and causes the person to lose immunity and protection against common infections. A person infected with HIV may suffer from severe weight loss, lung infections, and brain infections, amongst other symptoms. Currently, HIV is not curable but is treatable.
Chapter 12
Explain what Syphilis does to the body
A person infected with syphilis may suffer from common symptoms such as rashes and painless sores. If left untreated, syphilis may lead to blindness, inability to move parts of the body, heart failure, insanity and even death.
Chapter 12
Explain what gonorrhoea does to the body
Symptoms and signs of gonorrhoea are swelling, pain, and pus at the infected areas. If left untreated, the bacterial infection can spread and affect other organ systems.
Chapter 12
How do you treat gonorrhoea and syphilis and why does it work?
Since gonorrhoea and syphilis are both bacterial infections, antibiotics can be used to treat them.
Chapter 12
State 6 ways to prevent getting infected with STIs and control their spread
We can avoid having multiple sex partners, avoid sharing instruments, ensure that only needles that are free from bacteria and diseases are used, using condoms during sexual intercourse to reduce the risk of infection, not abusing drugs or charging injection needles and ensuring that donated blood is screened for HIV and safe for use.
Chapter 12
What are some complications of abortions
Parts of the sexual reproductive system may become infected or damaged which can lead to the disruption of the system’s function and may cause difficulties in getting pregnant again
Chapter 13
Define electric current
An electric current is the rate of flow of electric charge.
Chapter 13
State the SI unit of current
The SI unit of current is the ampere (A).
Chapter 13
Describe conventional flow
Conventional flow is the flow of current from the positive terminal of a battery to the negative terminal
Chapter 13
Describe electron flow
Electron flow is the flow of electrons from the negative terminal to a positive terminal
Chapter 13
How is a circuit diagram useful?
A circuit diagram helps us see if the electrical components are connected correctly
Chapter 13
List the components of an electric circuit.
Wires, dry cell, switch, light bulb and resistor
Chapter 13
What is in a series circuit?
In a series circuit, the electrical components are joined one after another to form a single loop. Electric current passes through a single path in a series circuit.
Chapter 13
What is in a parallel circuit?
In a parallel circuit, the electrical current is divided into branches. Electrical components are connected in each branch. Electric current passes through all branches.
Chapter 13
Describe and explain the difference in the brightness of two bulbs when they are arranged in series and in parallel
Bulbs are brighter when arranged in parallel because
current is faster.
Chapter 13
How would other circuit components be affected if one component is removed in a series and parallel circuit?
The components won’t work in series, but will still work in parallel circuit.
