Human Organ Systems

Question 1

List the main parts of the digestive system.

7 marks

Answer 1

• Teeth
• Saliva
• Oesophagus (gullet)
• Stomach
• Small intestine
• Large intestine
• Liver

Question 2

List and explain the stages of digestion.

12 marks

Answer 2

1. Ingestion - the entry of food through the mouth
2. Propulsion - food leaves the mouth when teh tongue propels it into the oesophagus
3. Mechanical digestion - chewing and breaking food into smaller bits, such as in the stomach
4. Chemical digestion - enzymes break down complex food molecules into their building blocks, e.g. proteins become amino acids
5. Absorbsion - most nutrients are absorbed primarily within the small intestine
6. Defecation - undigested material is removed from the body as faeces

Question 3

Describe and explain the different types of teeth.

8 marks

Answer 3

1. Incisors are the teeth at the front of the mouth. They are for cutting through food.
2. Canines are positioned next to the incisors. They are used for ripping apart meat.
3. Premolars are positioned before the molars. They are used primarily for chewing food.
4. Molars reside at the very back of the mouth. They have flat crowns and are used for chewing food.

Question 4

What is peristalsis and how does fibre affect it?

3 marks

Answer 4

Peristalsis is the involuntary contraction and relaxation of muscles throughout the digestive tract. This pushes food along the digestive tract. Dietary fibre increases the weight and size of feaces and softens it.

Question 5

How are the villi in the small intestine adapted to their function?

1 mark

Answer 5

They have lots of surface area for absorbsion of nutrients.

Question 6

Describe the function of the skeletal system.

1 mark

Answer 6

The skeletal system supports and protects the body.

Question 7

What are the main organs in the skeletal system?

1 mark

Answer 7

Bones

Question 8

How du humans move using bones, muscles and tendons?

2 marks

Answer 8

Muscles and bones are connected by tendons and ligaments. When a muscle contracts, it will pull the bone around the joint, e.g. flexing your arm.

Question 9

What are joints and how do they aid movement?

2 marks

Answer 9

Joints are hinges where two bones meet. They allow movement in the body.

Question 10

Describe how an antagonistic pair of muscles cause movement.

2 marks

Answer 10

Triceps and biceps are an example of an antagonistic muscle pair. The bicep causes your arm to flex, whereas the tricep straightens it.

Question 11

Describe the role of the veins and arteries, and how blood circulates around the body.

3 marks

Answer 11

Veins and arteries are both types of blood vessel. Blood is pumped around the body by the heart. Arteries carry blood away from the heart and veins carry blood back to the heart.

Question 12

Describe the role of the lungs, diaphragm and ribs in breathing.

3 marks

Answer 12

1. Gas exchange occurs within the lungs.
2. When we inhale, the diaphragm flattens and the ribs expand up and out.
3. When we exhale, the diaphragm becomes a dome shape and the ribs go down and in.

Question 13

How are the alveoli adapted to gaseous exchange?

3 marks

Answer 13

Alveoli sit at the end of the bronchioles, like grapes on a vine. They have a large surface area covered in capillaries, so gas can get in and out of the bloodstream quickly and easily.

Question 14

Describe the stages in human development from fertilised egg to death.

11 marks

Answer 14

1. Fertilised egg
2. Zygote
3. Embryo
4. Fetus
5. Newborn baby
6. Toddler
7. Child
8. Adolescent
9. Adult
10. Elderly
11. Death

Question 15

List and describe the organs of the male and female reproductive systems.

30 marks

Answer 15

Male
1. The testis or testicle is made up of many coiled tubes. The tubes produce sperm and the cells in between the tubes produce testosterone
2. The glans is the sensitive tip of the penis. It contains nerves that start of the reflex causing ejaculation.
3. The foreskin covers the sensitive tip of the penis.
4. The penis becomes erect during sexual excitement as it contains spaces that fill with blood.
5. The scrotum or scrotal sac holds the testes.
6. The urethra carries semen from the sperm duct to the tip of the penis. It also carries urine, but a small valve prevents this happening during ejaculation.
7. The prostate gland produces the seminal fluid, which makes up 99% of semen.
8. The sperm duct carries sperm from the testis the the urethra.

Female
1. The vagina or birth canal receives the penis during intercourse and is the ‘way out’ for the baby at childbirth.
2. The inner lining of the uterus has many blood vessels for nourishment of the fetus if fertilisation and imlantation occur.
3. The muscular wall of the uterus, which will contract to squeeze the baby out during childbirth.
4. The ovary contains follicles that develop into eggs, the female gametes. It also produces two female hormones (oestrogen and progesterone).
5. The funnel of the oviduct collects the egg at ovulation.
6. The oviduct or fallopian tube carries the egg towards the uterus. Fertilisation usually occurs in the first third of the oviduct.
7. The uterus or womb is the chamber in which the fetus develops. During pregnancy, it increases in volume from 10 cm³ to 5 000 cm³.

Question 16

Distinguish between asexual and sexual reproduction.

2 marks

Answer 16

Sexual reproduction is the production of offspring by the combination of genetic information of male and female. In asexual reproduction, one parent copies itself to form a genetically identical offspring.

Question 17

Describe puberty and adolescence in males and females.

12 marks

Answer 17

Males
1. Muscles grow larger
2. Voice gets deeper
3. Penis and testes grow larger
4. Aggresive tendencies increase

Females
1. Menstruation starts
2. Breasts grow larger
3. Maternal tendencies increase

Both
1. Armpit and facial hair starts appearing
2. Height increases
3. ‘Mood swings’ start happening

Adolescence is the period following the onset of puberty during which a young person develops from a child into an adult.

Question 18

Describe the stages of the menstrual cycle.

10 marks

Answer 18

• Day 1-5: The lining of the uterus breaks down. This is called menstruation or a period.
• Day 10-14: the lining of the uterus becomes thicker with extra blood vessels.
• Day 12: The egg is released in ovulation. A woman’s body temperature rises by about 6°C.
• Day 12-17: Because sperm can live for 48 hours and an egg can live for several days, a woman can become pregnant at any time from day 12 to day 17 of her menstrual cycle.
• Day 28: The lining of the uterus is now ready to receive the fertilised egg. If no egg is fertilised, the lining of the uterus breaks down and the cycle starts again.

Question 19

Describe the function of the placenta and the umbilical cord.

3 marks

Answer 19

The placenta develops after implantation. It controls the flow of nutrients and materials between the mother and the baby.
The umbilical cord connects the placenta and the baby.