Biology Paper 2

Question 1

Gametes

meiosis

Answer 1

Meiosis takes place in reproductive organs. 1 cell forms 4 gametes (genetically different) gametes have 23 single chromosomes
Sexual reproduction is the fusion of male and female gametes (23 pairs of chromosomes)

Question 2

Genetic Engineering

Answer 2

Use enzymes to isolate gene, transfer gene into plasmid (vector) transferred into target organism. always transfer gene at an early stage in the organisms development.

Question 3

Three Domain System

Answer 3

Three Domain System
-archea, primitive bacteria found in extreme conditions (hot springs)

• true bacteria, the kind that live in the human digestive system
• eukaryota, animals, plants and fungi (protists)

Question 4

Classification

Answer 4

Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 5

Homeostasis

Answer 5

Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions four function in response to internal and external changes.

Receptor’s detect changes in the environment (stimulus) and pass information to the coordination centre

coordination centre receives and processes information and passes it on to the effector (muscle or gland) carry out response and restore optimum level

Question 6

Reflex Arc

Answer 6

Nervous System enables humans to react to there surroundings.

When you touch a hot object the stimulus (heat) is detected by a receptor (skin). Electrical impulses pass from receptor along sensory neurons to the CNS. At the end of the sensory neuron there is a junction called the synapse. At the synapse a chemical is released this diffused across to a relay neuron in the CNS where it triggers a electrical impulse. this electrical impulse reaches another synapse, once again a chemical is released which triggers an impulse in the motor neurons and goes to the effector where a response is made. Muscle now contracts and pulls the hand away from the heat.

Question 7

Endocrine System

Answer 7

How body is controlled by chemicals called hormones

Pancreas - hormones involved in controlling blood glucose levels

Ovaries and testes release hormones involved in puberty and reproduction

Thyroid gland produces hormones involved in growth and regulating basal metabolic rate

adrenal glands - fear, stress hormones

Pituitary gland (brain) - master gland releases different hormones depending on conditions, hormones act on other glands, cause hormones to be released

Question 8

Diabetes

Answer 8

Type 1 - not enough insulin, monitor glucose levels and inject insulin if blood glucose rises too much

Type 2 - body cells stop responding to insulin

• diet containing a controlled level of carbohydrates
• advised to take exercise
• caused by obesity

Question 9

Menstrual Cycle

Answer 9

Follicle Stimulating hormones (FSH) - causes an egg to mature in ovaries and triggers ovaries to make oestrogen, released by pituitary gland

Luteinising hormone (LH) - causes egg to be released (ovulation), released by pituitary gland

Oestrogen - maintaining uterus lining in case egg is fertilised, and stopes pituitary gland from releasing any more FSH

Progesterone - Once egg is released ovary produces progesterone which stops pituitary gland from releasing FSH and LH to prevent any more eggs from maturing or being released. Keeps lining of uterus thick in case egg implants. if fertilisation does not take place progesterone levels fall. (period)

Question 10

Treat Infertility

Answer 10

FSH and LH are given to women (fertility drug)
- causes them to ovulate more then usual

In - vitro fertilisation (IVF)

• takes place outside the body
• mother treated with FSH and LH
• once embryo is tiny balls its inserted into mothers uterus
• success rates are not high, emotionally stressful, physically demanding (mother), can lead to multiple births
• very expensive, not all embryos are transferred

Question 11

Tertiary consumer

Answer 11

Tertiary consumer - eats secondary consumer

Question 12

TSH

Answer 12

TSH - thyroid stimulating hormone

Question 13

Carbon Cycle

Answer 13

Taken in by plants (photosynthesis), brings carbon into cycle
Released back through aerobic respiration, returns carbon into the cycle

Question 14

Glucagon and Glycogen

Answer 14

Glucagon triggers glycogen stores to be converted back to glucose

Question 15

adrenaline

Answer 15

adrenaline makes heart beat faster so more oxygen and glucose are delivered to brain and muscles (fight or flight)